So, I guess my announcement is that, some of you know this already, because you were there, but, last week the Reduced Risk Pesticide List was approved by the Commission on the Environment and final approval for the year. So, as a reminder, every year we, have work meetings, we go through the list, we try to take the bad stuff out, put the good stuff in, and then we run it through a public hearing; or we actually have a public hearing, not devoted to the list per se, but to general IPM activities on city properties. And then we introduced the list to our Commission on the Environment. They have the power to approve, disapprove, or change this list. And it's important for us to make sure we have transparency with the public and, you know, kind of a conversation going between the city staff in particular and the public.
And that's what the commission meetings are for. They've been really extensive in the past couple of years as you know, because of the Roundup issue. This year, I feel like the pressure, or the participation at least lightened up a bit and there were actually, there was no opposition in the room last week at the commission meeting, for whatever reason. I like to think that we're getting the word out that you all are doing a great job and everyone's committed to all this. So, I'm happy about that. The potentially confusing thing now though is that the schedule has changed. So, we're not, it's no longer a 2018 approved list or reduced risk pesticide list. It's just the current list and there'll be a "list last updated" on it. So, this is just to ease other people's confusion when we had a 2017 labeled lists and it's 2018. And what happened? Am I looking at the right list? There's only one list posted. It's the current list approved last week. The next time we'll have to revisit, this is going to be next summer, starting in July. So, it's a July, August, or August, September through the process. So, that's, that's where it's at. And what I'm going to do right now is go through quickly what the commission saw, a few of the slides the commission saw for those of you who have already seen it, you can like play with your cell phone or something. And mostly just highlight what the changes are in the list. They're pretty minor, but there's a couple that you really need to know about.
So, just Fyi, this is the trends, the pesticide use trends most up to date. The red are tier one products at the time of use. So, you'll see this is 2010 here, leading up through the full year of 2017 and in 2015 is when glyphosate became a tier one product. So, a lot of what you see is yellow in these previous bars and are now red, right? And it's the right trend. This is all in city pesticide use and doesn't include public health use, which wouldn't make a difference on this one so much. But the tier, you know, helps us focus our efforts. And if you add up all pesticide use for tier one products in city, it's been a 96% reduction. And for that, you know, you guys can give yourselves a little hand I think because that's amazing.
And that the key here though is that--explaining that last 4%, you know, or communicating why we don't have complete elimination of tier one products is always a challenge. And, that's what we tried to do in the commission meeting. We cited some of the data in human terms. This is Rec Park only, all parks, 60 gallons of active ingredient in 2010. You know, active ingredients like 53%, I think, with Roundup custom, it's different for different products. So, this is mostly Roundup or glyphosate and Garlon and Turflon. And in 2017, 1.8 gallons on 3,500 acres of land for active ingredient, right? So, you multiply that a few times for what's in the bottle. But that's great. And, and that's something I think the commissioners really heard. And you know, that last 4% is all about stubborn weed problems. That looks stubborn.
Have any of you ever, ever done this? Yeah. Okay. Thumbs down. Okay. To bata grass and Rec Park had some great examples of sort of this last 4% problem. And you know, I talked about all the trainings we've been having and try to get good photos of you all. It was really hard. And also pointed out, and I don't, maybe you haven't, don't know about this yet, but we, we have a new dashboard for reporting use data. It's interactive. It's better than the last interactive one we had. It's on the website. You can fiddle around with it and look at the data in a lot of different ways and it lets us update things a lot easier now. We used to have to do weeks of checking for like, we have unit issues and so forth and now we've got a lot of it automated so that's good.
I reported to the commission about, about other cities are updated and monitor to see other cities and their progress. You may know Richmond has a total pesticide ban. Their city staff has been asking them to roll that back because it's not meeting their needs at this point. That's what we've been hearing. Irvine had an ordinance allowing only organic products, and some of those were a danger labeled, unfortunately. They are returning this year to a limited use of some products that we wouldn't use actually. Especially I think bind weed was a big one. A lot of median strip problems. They have a lot of median strips. A lot of boulevards. So, the point there was no one--no city our size has been able to completely ban the tier one products, but we've been really out front and reducing it and restricting it and reducing it.
And you all have been really out front. I told him about future activities. This is really just, I'm skimming through this because, you know, it all, but we're still emphasizing holistic programs like Bay Friendly where we're not just thinking about pesticides but we're thinking about what we're planning and water conservation and all that stuff, biodiversity. And we are now, you know, going into the future, we're working more on pest prevention by design in affordable housing and Pestec. We're looking for funding for this. But we're going to do some of it no matter what in phase four of the RAD affordable housing conversion. So, that's turning SF public housing--it's sort of a semi privatization of it. But it allows for renovations of some really nasty, nasty housing situations and we're building pest prevention into that. And some of you are involved in this too.
We have the ongoing, pest prevention guidelines for landscapes that we're slowly churning our way through. One meeting per month. This is not funded either, so it means it goes a little slow, but it is happening. And then Public Works had a report on their activities, Rec Park a report on their activities. And here's what I actually have this up here for is just to clarify what the new changes are to list. The list itself is all posted now. I'll send you an email later today with the link, but it is on our website now. As a reminder, the current restrictions on tier one products are listed here. The 15 feet from the paths restriction. The more requirement from our specific notice, public notice. Blue indicator dyes. No use on blackberries. No use for purely cosmetic purposes, which is a tough one.
No broadcast spraying with a boom except on the golf course, Harding Park. No use on areas frequented by children, which you weren't doing anyway. A requirement to make sure that the contractors are on board, when we have a landscape contractor in particular, they have to know what's going on. And, also the requirement for direct supervision by a certified applicator when there's a tier one herbicide being used. And that means someone has to be on site with the license. We are, we went through all that and previous years and a lot of those were due to public request or partially due to public requests. And we wanted to highlight that for the commission because they want, that's one thing that's really important for them is to know that we're listening to them and to the public. The changes are, some of those are now expanded to all herbicides and really some of the these make sense anyway.
I mean, if you're going to expand public notice, you should just expand it for any herbicide treatment out in the parks. So, people want to know where exactly things are being treated, not just a sign that says weeds, right. It should be a sign that says let's see, "blackberry along this trail, five, 10 feet along this trail," or something so they know where it is. So, that's all herbicides, blue indicator dyes for all herbicides. The public commission wanted an expansion of the berries definition to anything human edible. So, that's mostly blackberries, but there might be a few little stray, I don't know, does anyone have shad berries. There might be a few huckleberries. I don't know. You're not doing it anyway, but it's now an official restriction and the contractor training, which should be happening no matter what.
I mean the contractors need to know that we have these restrictions. So, these are now in place and approved by the Commission and we have 10 months of not worrying about this whole thing, which took a huge amount of time by the way, but it's worth it. There's also a prohibition, I should have said. on green roofs and green walls. And that's really because we want to understand what it means to manage these things. First of all, we assume that you don't need it on a green roof. We really hope they don't need it on a green roof because it's right next to where someone's working or living. But if they do, we want to hear an exemption request, right? So that we know how this should be restricted and, and then we tighten the format of the list. It's more logical now.
So, some of you already went through this a year ago almost, but we added a generic boric acid ant bait, tier one, smoke bombs for rats. So, those were the two-tier ones that were added. The rest of it is mostly administrative. I mean, mostly product name changes, addition of some tier two products that, our potential alternatives to glyphosate and like Lifeline, for example, Amazamox. So, that's all posted. I'm not going to go through the whole list with you here. I just wanted to let you know that it's all happening. It's all done for this year. I did want to just say that.
One reason we really wanted to get someone to talk about palm trees is because it's been an ongoing challenge for a lot of people to deal with pest management problems that come up with palm trees that are the wrong species are in the wrong place and usually it's an extremely expensive operation to replace them. You know, we've had this come up numerous times over the past 15 years and we haven't had the chance to bring in someone who actually knows about palm trees and can talk about what we should be paying attention to when we're choosing what to plant. And you know what the site characteristics are like and what are the best species and so forth. So, I'm really happy Jason, you could join us today.
Thank you. Thank you very much. Let's see if I can clip this on. So, I am a plant person and I'm here to talk to you about palms, which are my area of expertise, having volunteered here at the botanical garden for a long, long time. And I've been at Flora Grubb Gardens, which you may know is a retail nursery down in the Bayview district. We have a wholesale operation in Southern California where we grow palm trees and other kinds of palms. Not all palms are trees, which I'll discuss.
So, as you know, the healthiest plant is the plant that's best adapted to the site it's planted in and that's best cared for. A lot of the commercial palms in California are grown in Southern California and are better adapted for hotter climates than the one that we're in. Some are adapted to San Francisco. But San Francisco has an unusual climate compared to other urban areas of California aside from say Monterey and Santa Cruz. So, the palms that we get from the general commercial growers, may not be the right palm for the site in San Francisco. They may be, but they may not be. My book is about designing with palms and it targets designers as well as palm fanatics and plant collectors. For the designers, what I'm helping them do is choose the right species for their designs. So, for our purposes, the book actually addresses that same question, choosing the right species for a location, so as to avoid some of the pests and fungal diseases that we get on palms.
So, I'm going to go through and describe a little bit about the palm family and show you a lot of beautiful pictures taken by my collaborator, Caitlin Atkinson. Any ugly pictures are taken by me in this slideshow. I don't want to attribute the ugly pictures to Kaitlin. But I did include a bunch of new photos into this slideshow. So, San Francisco's very cool and moist, right? And it's not common to find this super mild climate anywhere else in North America aside from coastal California. But there are other places in the world, including some of the high- altitude cities in the Andes from which a lot of the plants you see literally right out the door here come. And so that is the source for some of the palms that actually are better suited to our climate than the ones often miss planted.
So, those are just a few bits of information before I get into it. So, the palm tends to have an iconic shape and image. People know what a palm tree looks like. If you're five years old, you can probably scratch out a palm tree. It's one of the earliest plants depicted in human art. They're ancient petroglyphs in north Africa and in Saudi Arabia of palms 5,000, 6,000 years old. The, some of the oldest coins in the western tradition have palms on them. Part of the reason for that is that palms, date palms in specific represent a source of food and shelter and a place where water is available when you're living in the Middle East in the desert. This plant that has been under cultivation as long as figs and olives and pomegranates is the tree of life. Well, this is the tree of life for the tropical Pacific and Indian Ocean.
This is the coconut palm. Palms are the third most economically important plant family after grasses and legumes. So, when you think of grasses, you think obviously of wheat and corn and all the other staples, rice, and then legumes are beans. So, soybeans and all the other beans. Palms are the next on that list. We're not super conscious of that here in more northerly latitudes. But wherever palms grow, the people who live among them use them and in some cases use an enumerable set of parts to that palm. So, for example, in India, the Palmyra palm is celebrated for having 800 different uses in an ancient poem. And the coconut palm probably has, you know, 300 or 400 different uses. It ranges from food, there's water in those coconuts. There are materials that you can use to build, for example, a thatched roof. You can even use the trunks to build posts that will last for some years. You can make wine and sugar out of them. So, just a sense that palms for us tend to be ornamental plants. But for a lot of the rest of the world, palms are work horses.
So, here in California, the most common palm that we see is the palm on the right, which is the Mexican Fan Palm, Washingtonia Robusta. It's native to central Baja California. It's unbelievably adaptable. I like to call it the cockroach of palms. It will grow anywhere from foggy coastal California down to Baja California. It'll grow in Florida. It'll grow in Hawaii. All of these places in the U.S. it is very easy to grow. It's super fast growing. It hangs onto its dead leaves for the majority of its life, at least, within our cultivation, time frame. And it can be a problem because it's got these dead leaves at hang onto it. And in a landscape, it's helpful to remove those and it takes a lot of effort to do so, and it can be dangerous. They do reach a certain age at which they start to lose their leaves spontaneously when they're dying, when the leaves are dying.
And so that plant on the right in that photograph from Santa Monica, is actually at the stage where the dead leaves just peel right off. And some of those Washingtonia Robustas, Mexican Fan Palms in San Francisco are doing the same. So, around the 16th and Mission and 24th and Mission BART stations, those are some of the tallest oldest one's in San Francisco and they are actually kind of at the age where they'll hang onto a few leaves, but they mostly just dropped the dead leaves at this stage. In the middle is a hybrid between the one on the left, which is our native desert fan palm. So, the palm on the left with the skirts, the shag, that photograph was taken in the Indian Canyons Tribal Park up above Palm Springs. It's just a 10-minute drive outside of Palm Springs. This is the palm that's native to California and Arizona. It's also native to Northern Baja California.
This is a palm that you'll see all over the place from Redding obviously down into the low desert. It's super cold hardy, but it is not very tolerant of humid coastal conditions, even in Southern California and it's prone to diamond scale. So occasionally you'll see this spect and plant it in San Francisco. And for the most part, those plants, those palm, the desert fan palms planted in San Francisco are not long for this world, because they get this diamond scale in these humid conditions of marine layer, which eventually kind of eats away at them and they get weakened and then they're killed off by any number of other fungal diseases, particularly pink rot. So, at the park in Hayes Valley, there are four of these planted and they're just slowly dwindling. So, that's a classic example of species selection that doesn't work for the benefit of the plant and the landscape.
But there are alternatives to this plant. So, the middle plant is the hybrid between the two species and that one has some of the tolerance for the human conditions that the Mexican Fan Palm on the right has. And you can sort of see in that photograph the two palms in the middle are the hybrid, and then those ones off in the distance are the Mexican Fan Palms, the skinnier, taller one. So, that's just one example of how species selection can help you prevent or avoid some of the fungal diseases. But there are some other downsides on the Mexican Fan Palm that have more to do with appearance, that I can talk about a little bit later. So, the effort here is to look more closely at palms. And so, that iconic picture both here in California and here down in Florida, kind of gets in the way of our really examining like what are the parts of palms.
What forms do palms take. There are 2,500 species. They range from being little under story plants in the rain forest or you know, just any kind of forest, little tiny plants that you might mix up with a fern, to bamboo light clusters. Little like sort of shrubby palms that have really thin bamboo like stems. There are vining palms. So rattan, which you know, of as the material used for furniture and some other uses, there are three or 400 species of these rattan palms down in Southeast Asia as well as down in tropical America, those are palms, but they're just climbing up in the, in the rain forest and you wouldn't necessarily notice them as palms. And then there are other kinds of shrubby palms. Palms that just grow leaves out of a stem that stays underground, that stays in the soil and then shrubby palms that are kind of low but still make trunks. So, you end up with kind of a paradise island effect if you prune and groomed them correctly. And I'll show you pictures of those as well. So yes, we talk about palm trees, but in fact the diversity of the palm family and the forms that it takes is quite high and botanists, consider the palm family to be a rather diverse plant family.
So, this is sort of the classic view of palms in a landscape. They are very tropical looking palms are the sort of superlative foliage plant. They have the biggest leaf in the plant kingdom, 80 feet long is the tallest, longest leaf in the plant, sorry, in the plant kingdom and it is a palm from east Africa. On the left we have a fan palm called bismarckia. On the right we have a feather palm called beccariophoenix. Both of these are from Madagascar. So, the two big divisions in the palm family are the fans and the feathers. The fans on the left, the feathers on the right. The fan, I was talking about with the Mexican Fan Palm, the feather is that coconut palm in that first slide. This is if you don't have a fan shaped leaf or a feather shape leaf on a plant, it's probably not a palm. So, sometimes we look at cortaline australis and we call it a dresillias palm. But the leaves on that plant are spear shaped or dagger shaped. They don't have that complex feather or fan shape. Also, that is a branching plant and palms in our palette do not branch. I'll show you a picture of a palm that does naturally branch.
So, this is an alternative view of how palms can be used in a landscape. This is a landscape in Santa Monica. That silvery fan palm that is a shrub down in the grasses at the meadow-y vegetation, is naturally a shrub. It has multiple stems that arise from the same root stalk. It's called chamaerops humilis argentea, the Blue Mediterranean Fan Palm it is native to the Atlas Mountains of Morocco and Algeria. And it's one of these incredibly hardy to cold and to drought plants. And it happens to be a palm and it has some really good uses in the landscape and it's a pretty hard plant to kill. So far, we haven't really seen any big problems with it. It's fairly new to the market. It's about 20 years into the market. It is a blue form of the much more common green Mediterranean Fan Palm, which we have been seeing for many, many decades, probably centuries in California. So anyway, this is a vision of using palms in a landscape that kind of defies that tropical stereotype. Part of the effort of my book is to defy the tropical stereotype. Get people to think about using palms in different contexts because they have particular aesthetic and functional uses in a landscape design.
What's that? That one you the Blue Mediterranean Fan Palm or the Blue Atlas Mountains. It does great. I planted... I gorilla planted, don't tell the police, two little three gallons of that species in a sandy little median that had gone unplanted, right before the big five-year drought that we had. So, it got about two months of rain and those plants are still growing and they're living in sand and there they got rain. They've had only rainfall in their entire life. I can't tell you they're growing fast, but they're doing perfectly fine and they look fine. So, that's as tough as a plant gets in San Francisco. So, the effort I would love to see is to expand the palate of palms that we use in San Francisco. They're not going away. Of course, I love palms.
A lot of people hate palms. I think part of the reason for that is there's such bold plants. So, a friend of mine, a designer whose work is in the book, talks about how especially these fan palms embody this kind of explosive energy. It's like you took a photograph of an explosion in the midst of happening, you know, in the middle of that explosion and you've got all this energy, this radial energy popping out. And in this case on the left and this, this is called a Blue Mexican Fan Palm. So different from that Mediterranean Fan Palm. This is actually from Baja, California. It grows as close as 10 miles from the California border. It actually grows in the same habitat as that desert fan palm, the native one. But it happens to be more tolerant of our conditions here on the coast.
It's more drought tolerant, slower growing, not as big. In any case, the introduction of new species I think will help avoid some of the pest problems that we, that we see on the palms. This one on the left, this brahea armata, the Mexican Blue Palm. It is growing down in Atherton where temperatures in this garden have dropped below 20 degrees more than once, in the 25 years that the gardener has been working there. And what you see coming out of that crown are the flower stalks. So, hundreds of thousands of flowers on those flower stalks. A really great source of nectar and pollen for pollinators. And again, it's a palm that's really well suited to California ornamental landscapes. Probably better away from the ocean, I must admit, based on its desert origin. So, I've seen them do better on the east side of San Francisco.
Not so great over here on the west side of San Francisco. On the right is the Andean Wax Palm. This is a photograph taken in Ventura. This is a palm in the genus cirosilon [?] 29:22. All the members of this genus are from the mountains of South America, from the Andes. They range from Venezuela down to Bolivia. They are all high altitude, relatively high-altitude palms. One of the species in this genus of the wax palms is from an altitude of 11,500 feet. So, consider, you know, that's as high, higher than Tioga pass and Yosemite, but it's on the equator. So, the temperatures there are quite cool year-round. If you go any higher than where that plant grows, they get frost many nights of the year in habitat. This particular species is also from a relatively high altitude. These are Cloud Forest Palms. So again, these are palms from areas where a lot of the plant material you see in the botanical garden comes from. A lot of our best ornamental plants in California or sorry, in San Francisco, come from these cloud forest habitats. And this botanical garden actually has the best collection of this genus outside of South America, because our climate is so well suited to this genus.
So, palms are flowering plants. They're monocots there related to grasses, orchids, lilies, bromeliads, agaves, aloes, all the monocots. So, they don't make secondary growth in their trunks. They're not really woody trees. The stem on a palm, has xylem and phloem them growing or moving in a spiral up the trunk. Basically, the entire trunk is sort of alive with the vessels and they were very fibrous. They have tremendous 10 styles strength. If you think of Anderson Cooper reporting from a hurricane, the plants in his background are usually palm trees blowing around in the wind. The leaves are very flexible. The trunks are very flexible. They may shed their leaves during a really severe wind event. Occasionally there'll be uprooted. But less commonly, they'll be broken. They don't break very easily. There's are some exceptions to that.
But in general, palm stems are quite flexible and very strong. So, occasionally I'll be hired for a consultation project where homeowners or you know, homeowner's association, they're concerned about the height of their palm tree. They're worried that it might break or fall over. That's the really the least of their worries. But because they've got such a tall stem in some cases like that Mexican Fan Palm and because there's this crown blowing around up above, they look kind of out of kilter to people. But in fact, they're very well suited to the structure that they have. Nonetheless, the photograph on the right shows a flower stalk popping out of a protective casing, a bract. Again, probably thousands of flower buds on that flower stalk. This is growing in Walnut Creek. It's a member of the genus butia. And on the right photo, just a picture from Hawaii of palms growing kind of like grassy little seedlings.
So, just a hint at their offense their genetic relationship to other monocots--to grasses and other monocots. A photograph of some pollination going on, on a sable palm on the left, on the right fruit in December on native desert fan palm. So, they're they are plants that have ecological relationships. They are involved in the web of life. They're not just, these sort of, architectural elements that come in on a flat bed truck and get planted like pretty maids in a row. So, on the right in this oasis down by Palm Springs, these fruits are going to be used by the coyotes, the foxes, the western blue birds, and the leaves are going to be used by a hooded Orioles to make their nests. They're hanging nests. And of course, the people of the desert use the palm. So, the people in the Aquia Indian tribes like take advantage of all the different elements of that beautiful fan palm that we think of as an ornamental for shoes, for shelter.
They even use the fruits for food. There's a flower made out of the seed. The fruit itself is sweet and can be made into a sweet beverage. So again, even in California, there are important human relationships with palms. And of course, that relates to us. And as much as we want to make sure that, you know, when people are interacting with palms, they're not interacting with, you know, as little as possible, a plant that's had to be sprayed with a pesticide or a fungicide. And so, by choosing the right plant, we're not, we're, we're putting ourselves in that position much less frequently. So, an illustration again of what palms are and what palms or not. So, on the left, the photograph shows trachycarpus wagnerianus in a garden Gernville as a super hardy, cold hardy fan palm from Japan and China.
So, up in the upper left corner is the palm. You can see the fan leaf down in the center of the photograph that blueish crown--Yucca, is not a palm. If you look at the leaf form, it is dagger shaped or spear shaped. But it does have that sort of palm form. It's got a trunk down below, that little straw-colored section. And then and then the crown up above. So, not a palm. So, on the right this might look like a palm, because it's got that feather shaped leaf. But if you look carefully at the way the leaves are emerging from this cycad, down in Georgia, they're all coming out at once and they're uncurling almost in the manner of a fern fiddlehead. So, palms have a single leaf emerging at the center at all times, and from a spear like structure and unfolding into the newest leaf, so that frond you can see the unfolding process underway.
The stuff is still folded together, up here, but on the apical end of the leaf, it's unfolded. And then here's the next spear coming up. So, that illustrates to you the way that palms develop. There's one bud at the top of each stem. So, if it's a single stem palm tree, like a Mexican Fan Palm, it only has one bud way up there in the crown. So, if that bud is damaged, it's going to take a while to recover. And if it's cut off, it's not going to branch. There's no new bud that's going to form on the side of the stem. There's again, there's no secondary growth on the stems of palms. And then on the right is just an illustration of kind of the folded-ness. The way, if you look carefully at a palm leaf, it is an unfolded leaf.
So there is a fan and there's a feather in the back, in the photograph, that one from Hawaii. Again, just another illustration. This one photographed here in the botanical garden. This happens to be that species from the highest altitude. This is ceroxylon parvifrons. And again, this is the leaf that's unfolding at the moment. And then this was probably the last leaf to unfold. And then as time goes on, each leaf has its career photosynthesizing and then is displaced from above by the newest leaves and then eventually, dies off and falls off. On the right is just a fan shaped leaf from another palm. That's just steps away from here. This is called trachycarpus princeps, but again, you get the sense for each part. Each segment of the leaf is a single fold. Same over here. Each segment is a single fold.
There are a couple of unusual species that have a slightly different structure to the leaf. So, this is called a fishtail palm. This is caryota gigas or caryota obtusa of which there are a few here in the botanical garden. This is from the mountains of Southeast Asia. And it has the, the primary feathers shape and then the secondary feather shape composing the primary feathers shape, if that makes sense. So, the leaflets come off of like a secondary rib that comes off of that primary rib. So, here's the primary rib and the secondary rib. And then all along here, these little leaflets that look like, some say, fish tails, I prefer to think of it as like a pectoral fin on a fish. And then on the right, another species that's blooming and fruiting here in the botanical garden. So, this genus happens to grow in the manner of say an agave. Where it has a vegetative phase, it gets bigger and bigger and bigger, and then it has a flowering and fruiting phase after which it dies.
So, that's also something to keep in mind when you're dealing with palms in the landscape. Particularly this would be, say in a park setting, where you're going to have to take this plant down when it's done with its lifespan just as you would like a big agave. So, that genus is called caryota and it's the fishtail palm. It's the only genus that has that bipinnate structure, the secondary feathers shape. So, this is another variation on the fan palm. So, there's basically two variations on the fan palm. There's the plane pinnate leaf, which is where the segments all meet at the center of the blade of the leaf right there. Like there's a little buckle and they all, they all converge on that center point. And then there's the costa palmate leaf. So, the costa palmate leaf it's also a fan shape leaf.
But there's a rib, which is the Latin word for, or costa is the Latin word for rib. So, that rib runs down the middle of the blade. And so, some of the segments converge on the rib and some of them converge right in the center, which is hard to see in this picture. This is a sable or Asana from Sonora. This is also growing down in Atherton also tolerated temperatures below 20 degrees. So, I'm giving you this information so that you can distinguish between different kinds of palm trees. And once you're in San Francisco and you've got so few different palms that you see in the landscape, it's a lot easier to use these tools.
Okay, so the parts of a of a palm leaf include the sheath. So, this is over here. This is called the Necal Palm. This is from the native New Zealand Palm. These are growing here in the botanical garden. This is the sheath of the leaf. The sheath surrounds the trunk and it connects to the trunk in a ring. And then there's also the petiole of the leaf, which I will show you here. So, the petiole is that kind of branch, like structure that connects to the trunk and then there's the blade of the leaf, which would be where all the leaflets are. This is the blade. This is the petiole and these are the leaf bases or the sheath. So, the sheath takes different forms on the Necal, it's an entire fleshy photosynthesizing part of the leaf. On some of the ponds, a lot of the palms that we see in California, only one part of the sheath is still alive and photosynthesizing and connecting the entire leaf to the trunk.
And the rest of the sheath kind of disintegrates. So, in the Chinese windmill palm, you might know the furry trunked palm, the sheath disintegrates into a fibrous mass. It's almost like, the, it's like a natural form of a fabric. But nonetheless that is connected all the way around the trunk in a ring, just as that perfectly greened sheath here is. It just takes on a different form. But now it's still connected. When it, when the leaves are alive, they're still connected and delivering, water and taking sugars down into the trunk. So, on this palm you can see below the crown, the remnants of those old leaf bases, the stubs that are still dried out and stuck to the trunk. And that would have been where the live vessels were on those old leaves.
So, the roots of palms are fibrous, they are wirey. They are not very thick, and they experience no secondary thickening, which means that when a palm root emerges from the base of the trunk, it is at its thickest diameter. And from there it will start to branch. So, as they branch, those branches are thinner and thinner and thinner as they go farther from the trunk. This is why palms are relatively easy to transplant as large plants because they continually make new routes from the base of the trunk. So, on these Washingtonians at Walnut Creek, you can see the many little fibrous roots that are coming out from the base and how they're easily intermingling with each other. Because of their fiberous nature, because they don't have any secondary thickening they can't really strangle themselves. Also, those roots have a career kind of the way the leaf has a career.
So, the roots will eventually some of those roots that are the oldest roots will give up and they won't be a part of the palms functioning as much anymore and there'll be succeeded by the new routes that are continually emerging for the base of the trunk. Again, this is why palms are relatively easy to transplant as large specimens. Not all palms are, but many are. This is an example of stilt root palms from a tropical environment. These are called walking palms. There two of them. And again, you can see the way that their roots are kind of intermingling with each other. This is just a really blatant, illustration of how the root emerges from the base of the stem. There's no taproot, etc. And then on the right as an example of roots coming out along the trunk of the tree. So, way up above the, the soil line and their function is actually not to absorb moisture and nutrients. Their function in this case is to fend off herbivores. They've got spines. So, you can see the branching habit of the root. And at the tip of each of these roots is a spine and their job is really much more about defense than it is about absorption. Of course, down under the soil line, it has regular roots that are doing their regular job.
So, just a shot of the fishtail palm and some Kentia palms, which are [? ] 43:44 in a nursery, in boxes, illustrating that palms can be maintained in small spaces with some success. Although in general, they're happier once they get in the ground. And this is a shot from the Transbay Transit Center with Washingtonia Robusta, the Mexican fan palm planted, at a large size in order to achieve a big impact early on in the growth of the park. These have root ball anchors as do some of the other tall palms in the park in order to keep them secure while the roots, get established into the medium there.
Did you say that you suggested the hybrid instead?
No. Generally, the hybrid is half as prone to the diamond scale. And so, unless you really need a thicker, heavier trunk palm, I would have, not avoided, but it wouldn't be a choice over the Mexican fan palm. So, a great planting of the hybrid is in front of the ballpark. So, those palm trees in front of the ballpark are the hybrid between the desert fan palm and the Mexican fan palm. So, here's that shot I promised you of the naturally branching palm. This is a genus from Africa and India called Hyphaene and it naturally branches in this dichotomous fashion. So, the next round of branching is going to be equal to this branching. So, it'll go up in perfectly symmetrical branches. I think the maximum number that's been counted is like 32 or something, It's quite an extraordinary sight.
On the right is the Australian Fan Palm, Livingstone Australis, photographed at the Huntington Botanical Garden in Pasadena. So, this is a really useful palm for us that's rarely ever seen. It's a fast-growing fan palm. It's not susceptible to the diseases that we see on the Washingtonia. And it'll tolerate cooler conditions than the Washingtonia likes, particularly in shade. It can, grow fine and under a large canopy. The only big old established tree in public in San Francisco is on top of Lafayette Park, underneath the canopy of blue gums. So, this is again, we're looking for different species to use. This is a good option, instead of, say a Washingtonia, where say on the west side of San Francisco in the fog belt, it's not gonna look so good. It's going to grow slowly. This one is not going to suffer those same problems.
An example of that vining palm, this is here in the botanical garden. This is a type of rattan palm. They are fiercely armed, quite beautiful, but you don't want it in your garden. So, look at all these stems climbing up into this photinia tree.
Other examples of palm forms that we don't see so often in San Francisco, this is in the botanical garden right over here. This is a bamboo palm chamaedorea costa ricana, very well suited to California and particularly coastal California, I'm sorry, and San Francisco. And then this is another chameadoria stolonifera. This one grows also kind of like a bamboo palm, but it's so small that it's almost a ground cover. And this is a perfect example of the forms that palms take that we're just not familiar with as much because we think about that icon, the coconut palm or the date palm. And then if you look carefully at this leaf, you'll see that it is feathers shaped. It's just that the segments, those folds are not divided from each other. You can also see the stolons for which it's named. So, it's got these stems that kind of climb outward from the center of the clump and they make new stems coming up here. So, that's how it spreads, not very aggressively, but nonetheless enough to function in this garden as a kind of ground cover.
This is [? inaudible 00:47:50]. This is another kind of bamboo palm. This is a garden in Cow Hollow. So, the habitats of palms, often include, and especially in North America, pines and oaks, this is not something we think about very much in California, but in fact, here in Florida, you can see the, the slash pine, pinus ilae as the canopy over sable Palmetto, which is the state tree of Florida and South Carolina. The Palmetto and then underneath, hard to see in this light, there is a ground dwelling palm called serenoa repens, the Saw Palmetto. And so, this is just a very natural assemblage of species and habitat. And so is this. Again, in the Indian canyons, tribal park up above Palm Springs. This is our native desert fan palm growing with the deciduous trees and fall foliage that are also native to this drainage. So, this is our native California Sycamore. These are some cottonwood trees. These are some willow trees. This is a slide just to give you a sense for how palms grow in habitat. They aren't all tropical, lowland, evergreen forest dwelling plants. They're not just tropical beach plants.
So, this is an example too of how to manage a palm from a young age into an older age. So, this is called brahea clara, same species, same garden to like five years apart. So, when, this is a roset plant in site, it takes up a lot of space because the leaves come out, they splay out and so, This is Flora Grubb's garden, my boss's garden in Berkeley. So, what she did was she pruned the lower leaves carefully. She didn't cut too much into the crown, but she pruned the lower leaves enough that she could have space around the palm, to use the open space that's next to it. And then as the palm got older, she didn't have to prune the leaves as much. And in general, with a palm, you don't want to prune green leaves very much because it takes away from the vigor of the planet.
It can reduce the health of the plant. It can alter the taper of the trunk and it can expose the plant to pathogens, especially airborne fungal spores. So, you know, she took a risk. It wasn't a big risk, but a minor risk and made it a very livable space. Of course, in our parks and other areas it's very important to have space around the palm and these are armed. So, there are thorns on these petioles. Not a huge deal, but nonetheless, best to keep those a little bit out of the way of the public. So here, underneath the canopy of this plant, you've got space because it's been allowed to grow up a little bit. She didn't prune it down to two or three leaves. She just, she left like 10 leaves in the crown and it was able to grow speedily enough to develop that crown, I'm sorry, that trunk and make space for her to hang out.
Okay. So, instead of the Washingtonian, I love to see you people use the Guadalupe Palm. So, this is the palm. It's on the median of Cesar Chavez. This is the palms that's in the southwest corner of Dolores Park. This is the palm from Guadalupe Island, which is the southernmost outpost of the California floristic province. Meaning, this is a California native by the measure of biogeography. It is a plant that grows in habitat with a race of the Monterey Pine. It grows with ragweek sanguinian. It grows with a lot of our native ferns. It grows with cenophas. This, it grows with artemisia californica. This is a plant super well suited to coastal California and even inland California to some degree. It's super cold hardy. It doesn't get very tall. It's not very fast growing. It doesn't have thorns on the petiole and as it ages it sheds its dead leaves spontaneously.
So, this is a plant that I find to be more pleasing in the fog belt. It's much better adapted to the cool summers. It's also super drought tolerant and it's not particularly prone to diamond scale, which is the thing that takes down the Washingtonian philifera and the hybrid. So, this is one that I really urge people to choose over the Washingtonia in many cases. Another photo from habitat. This is in South Carolina. Again, the Palmetto, the state tree of South Carolina. Sable Palmetto growing with, for the Quercus Virginiana, the southern live oak, and with the lob lolly pine on the coast of, outside of Charleston. Another palm that's used insufficiently in California, overall is the butia palm. Butia odorata. This is from Uruguay and Brazil. It's super cold hardy. It's tough as nails. It's drought tolerant. It also makes edible fruit at least on the east side of San Francisco, that's delicious. But it will tolerate the foggy belt quite well.
What kind of fruit?
It's called the jelly palm and it kind of has this flavor in between, like a loquat and a plum. It's actually delicious. It's one of the few ornamental plants with edible fruits that's actually delicious. So, I was down in our growing grounds, tasting a couple of different ones, last week.
So again, the Washingtonia Robusta, so question about a pruning. The Washingtonia robusta and a lot of palms can actually have their leaf basis pruned, to reveal that ring trunk. And, as long as that cut isn't deep into the stem, you can avoid problems with, the fungal diseases that fly in the wind. These are newly planted and so they've got relatively small crowns. You know, after a palm has dug from the field, it's going to lose a lot of its surface area on the roots and the crown is going to die back. And then it will regrow from that single bud up at the top.
So, one of the big problems in San Francisco and in California right now is fusarium wilt that's killing the phoenix canarianansys. Fusarium wilt is a relatively new problem up here. It's been a problem for a longer period down in Southern California. And when when a canary island date palm gets fusarium wilt, it will die. There is no treating it. And so, this is the classic example of a species selection that needs to change for the landscapes. And in California, unfortunately, there is no true alternative on the market. So, the best alternative is the true date palm, which is phoenix dacalifera. This is Majool. So, consider phoenix a fruit tree. Think of the many different kinds of apple trees we have. There are even more kinds of date palms. But in California we only have like 15 or 20 and have those not so many available for landscape.
Anyway, these got dug out of orchards down by Palm Springs, Indio, Coachella Valley because they're relatively cheap. They tolerate cold, they tolerate heat. They're not so great in the chilly summers here. But it is really the only alternative on the market that will fit the bill for a place like the Embarcadero because of the requirement for the trunk. Now, there are better species for this purpose. Chilean Wine Palm takes on the same grandeur of the Canary Island Date Palm on the left there, but here it is adult. But these adults are super hard to come by. There just aren't that many of this palm in the landscape to dig. And when they are available, they're extremely expensive because they're so few of them. So, here we are in the botanical garden again. Not that these are going to be a source for, you know, other landscapes, but as time goes on, they will become those majestic palm trees.
And our hope as growers down in Southern California at East [?] trees, the wholesale business that I also work for is to begin to replace the Canary Island Date Palm with this Chilean Wine Palm. A nice pair of them that you can see nearby is in front of the de Young Museum. There, two of them right next to each other and you can see them, you can tell the difference because they have this kind of concrete colored smooth cylindrical trunk, which is fatter than the Canary Island date palm and not as rough. This happens to be related to the coconut palm and it makes edible coconuts, little tiny marble size coconuts that are delicious and you can buy them online if you're interested. So, back at Trans Bay where the landscape architect chose to showcase some of these newer species, that are better adapted, he managed to get his hands on to one of these big Chilean Wine Palms.
This is quite a spectacular specimen. And then he also planted some other unusual species. This is called Parajubaya cocwaitis This is cocaya jublia. This is para jublias and indeed they're closely related. This one is from the Andes. So, this is another of these cloud forest species. This is a good alternative to like a Queen Paul, which I don't actually have a photograph of, but the Queen Palm is very commonly planted as a street tree here. It's only marginally successful in San Francisco. Some of them look great and do fine and others don't look great and don't do well. So, this is a much more vigorous plant in our climate because it's from this cloudy cloud forest atmosphere. And then a couple of other trachycarpus takil. There's a wealth of trachycarpus species that are well suited to our climate and that would be nice alternatives to that standard, Chinese Windmill Palm, Again, photographs of Trans Bay from above.
Here's that pair of jubaya kukwaites [? sp] I showed you from Trans Bay, older. As time goes on, the free leaf bases fall off and you end up with this almost coconut, like palm tree. It's quite graceful and beautiful. Fast growing. Loves the sunshine. And this was photographed in Bogota, 8,500 feet in the Andes in the botanic garden there. And here it is here at the botanical garden. You can take a look at it. I'm just right around the corner by the entry kiosk, two plants that are already starting to bloom. You can see the little coconuts forming on this infructescence.
Well, here's that, that wax palm genus in habitat when I was there in June. Again, cloud forest habitat, gorgeous palm tree, a nice alternative. Something that we don't really have in public landscapes here except in the botanical garden.
Not yet. We're trying, we've got about 501 gallons. So, this would be a great plant for parks. I don't think it would be a great plant for streets, at least within the regime that we currently have in San Francisco. The other fact about this palm, ceroxylon quindiuense, is that it is the tallest palm in the world. So, I got to see a 195-foot palm tree and habitat. Probably about four or 500 years old, just fantastic. Also, there's a cool waterfall. Didn't want to miss that. Oops. Wrong direction.
So, this is in Bogota. This is their sort of their main, ceremonial street. It runs up to the Catholic shrine on the mountain, where they have planted them as alley with this water feature down the center. And this goes for blocks and blocks and blocks. This was planted probably in the 1980's or early Nineties. And here it is at the botanical garden, just planted as a grove, quite spectacular. And here we have it in the botanical garden. These are the biggest ones, besides that one I showed you from Ventura, and then in the foreground, the Chilean Wine Palm that we talked about earlier. Oh, and the other thing about these is, these are already about 70 feet tall and they don't even have flowers yet. These are still teenager, not even teenagers. These are juvenile palms. They will open out their crowns the way you've seen in the habitat photo in the older botanic garden photo.
Okay, the wax covered trunk. And then these are some other para cobayas [?]. So, another species from the Andes, a really good alternative, ultimately, to the Canary Island Date Palm. This particular species is very large, fast growing, somewhat drought tolerant. And here are some down in Atherton in a hybrid, just to give you a sense for the look. This is a species on the right, this is the kentia palm. This is growing down in Santa Monica. This is somewhat marginal in San Francisco. They can be perfectly happy on the east side of San Francisco but they're prone to gliocladium rot, pink rot. So, it's been a bit of a battle over at the Academy of Sciences, because they are not super vigorous in the fog. They are slow growing. But where it's a little bit warmer, they're more vigorous and they tend to outgrow that pink rot, which is a chronic but not necessarily lethal disease. On the left an unusual palm from Australia, from Lord Howe Island, the same island this is from, this is called Hedis Epia Canaburia [? sp].
So these are the New Zealand Palm. This is the one from an island group north of New Zealand. This is called Rhopalostylis baueri. And then this is the one from the main islands of New Zealand rhopalostylis zapeta photographed here at the botanic garden. This is a great plant for San Francisco. It's kind of plant that doesn't like hot, dry weather, just like that wax palm and thus grows more vigorously for us than anywhere, for anybody else in California. Flower stalks are pretty showy and crazy looking like an undersea creature. It's a good plant for a park space. Not super drought tolerant, so it's not going to be a happy street tree. And doesn't love the sun, so. But again, we always think of palm trees as sort of these hot dry plants, but there are a lot of uses for palms that we don't think of because of that stereotype. Is there a question?
N-A-A-K-A-U is the Maori name. And the species name is long and complicated. It's Rhopalostylis, R-H-O-P-A-L-O-S-T-Y-L-I-S. And zapeta is the species name of this species, the other species in that same genus from Norfolk island and also from New Zealand. Baueri. B-A-U-E-R-I. So, it comes as a surprise to some people to learn that San Francisco is a place to grow certain poems that can't be grown elsewhere; or are poor performers elsewhere. This is a closeup of that Silver Mediterranean Fan Palm that I showed you from that grassy landscape. This is the regular green variety. So, this is a super common palm. This is the most adaptable palm I think I know of in the ornamental, palette. You can grow this in Hawaii. You can grow some in Miami, you can grow it in Seattle, you can grow it here.
There are about four of these in front of the cliff house and pots and they don't look terrible compared to most ornamental plants in that part of our city. So, it's super tough in many, many respects. It does great in the desert. It'll grow in the shade. It'll grow in the sun as long as it gets good drainage, it's basically indestructable. And there we have the Chilean Wine Palm over there at the de Young Museum. Again, you can sort of see how that might be a good replacement for the Canary Island Date Palm in its scale and its form. Here's a hybrid between it and that butia palms that I showed you earlier with the really blue, fronds next to the swimming pool. This is a hybrid between the jubaea and the butia. This one. And this was photographed in Walnut Creek, so you get some of the huskiness, the crown scale of the jubaea, but also the relatively short stature of the butia and that re-curved leaf and no fruit.
Again, livistona australis I showed you earlier. This is a really good alternative to Washingtonia. This is another species of liviistona. Just some features of color that are really beautiful. This is the hardest of all palms. This one you can grow on Long Island if you really want to. It is a ground dwelling shrub from southeast US, from South Carolina down to Mississippi and Florida. It's called the needle palm. And then on the right, this is the Chinese Windmill Palm that we know rather well from San Francisco. It tends to have some nutrient problems. It always looks a little bit yellow. Partly I think because it gets dried out a lot. It would prefer to be a little moister than we provide for and partly because it is just a kind of a greedy plant, likes a lot of fertilizer. Here's that wagnerarianus, which is basically that same species of the Chinese Windmill Palm, but with a more beautiful leaf.
And then some more trachycarpis. This one is trachycarpis ladisectis. This one is trachycarpis martianas. This is trachycarpis minceps. Again, a lot of different color form, shape available in this genus. All of these plants are from the Himalayan uplift. These are also kind of like the Asian version of the ceroxylon genus. So, these are all well suited to San Francisco. This is trachycarpis tequil here in the botanical garden. This is the one that grows the farthest west and very high about 7,000, 8,000 feet in the Himalayas. It grows in habitat with birch trees and fir trees and oak trees and Rhododendrons and all sorts of temperate flora. And a very unusual palm called arenga micrantha. This is just an example of sort of the farthest edge of plant introduction. This is a shrubby palm from the Himalaya, its a about maximum altitude, 8,500 feet. It's an example of the wealth of possibilities that are out there both for landscaping with palms and also for replacing some of the more common California grown hot weather palms.
So this is a list I'll give you guys of the plants that I discussed in the slide show, in order of the slides. A lot of botanical Latin. And then in terms-- I am not a pathologist, but these are the things that I see in my work. Fusarium wilt is by far the worst thing hitting palms in San Francisco and the only alternative is to plant different species and wherever possible, the best alternative is the Chilean Wine Palm. Parajubalia teralei which I briefly showed you at the base of those white waxy trunks here in the botanic garden, is a great alternative as well. It's much more unusual in the Chilean Wine Palm, but, but it is available. Diamond scale hits the Desert Fan Palms and the hybrid between the Desert Fan Palm and the Mexican Fan Palm. So, diamond scale looks like scale, but it's actually a fungal infection. It affects the lower leaves first. It's worse in the rainy season.
You'll even see it in our hot inland areas where there's a lot of rain in the winter-time. So, you'll see it effecting palms in Calistoga, St. Alena, you know, in the Salinas Valley and so by the time spring rolls around, the crowns have kind of dwindled from the bottom. And then by the time August, September, October roll around, the crowns have re-grown and they look fine. It's a problem. When you get super far inland, more like central valley, especially farther south, they are unaffected for the most part. The rain--the length of the hot dry season is enough that the distance from the fog belt is enough that they don't really suffer too much. Pink rot is a chronic disease-- I haven't really seen it on Washingtonia, but most other palms that we grow. It's not lethal in most cases unless the palm is otherwise weakened.
So, I bet it could kill one of the kentias in front of the California Academy but in general, and I think it's attacking a couple of King Palms on Castro Street, but in general, if the palm is reasonably vigorous, it just outgrows this chronic thing--Pink Rot, gliocalidium. But what happens, say with the Washingtonia, the Desert Fan Palm is, it's already weakened by the reduction of the crown from the diamond scale. And then the gliocalidium goes in and kills the bud because it's just such a weak plan at that stage. And then in general, you see some scale on palms in the landscape, not a whole lot. But palms in a nursery are affected by Mealy bugs, scale Mites, especially indoors of course. Once they get in the ground and as long as they're not being farmed by ants, the palms are mostly able to fend it off themselves.
Gophers love palms and agaves and they seem to be the sort of the worst mammalian pest on palms. Rabbits will eat that seemingly anything and especially palm leaves. I don't know if there are rabbits--I don't know if I've seen rabbits in San Francisco. There must be. And then the biggest pest threat right now is the Giant Palm Weevil from South America and Lower Central America, which has been discovered in Southern San Diego County. We're very concerned about what quarantine efforts are going into preventing it from expanding right now. It seems to just come across the border from Tijuana and that will kill big palms, particularly Canary Island Date Palms. It could be an enormous headache and a windfall for arborists taking down palm trees. And then once seen a couple of years ago, the Red Palm Weevil, which was sort of the Asian version of this South American Giant Palm Weevil. It was seen in Laguna Beach. It seems to have been eradicated. Hard to say if it really truly was. This has devastated the Mediterranean, particularly Canary Island Date Palms in the Mediterranean. So, these are weevils whose grubs eat the bud of the palm tree. So, if there's only one bud at the top of that stem, they devour it and the whole tree dies really fast. Question?
Okay. So, what's your hypothesis?
I'm guessing ... [inaudible].
Interesting. For years you guys didn't do a lot of printing on the Canaries. I don't know your current practices, What's your grooming practice? Yeah. Yeah. Okay. I don't know what to say about that. That's a really interesting situation. Sorry to hear it. Yet another yet another problem. Yeah. I think this is the last slide. So, open to any questions you might have. I'll answer as well as I can. Thank you so much for your attention and time. Appreciate it. And thanks for inviting me today. [applause]
Yeah, any animal rats, birds, particularly on canaries because they've got that--the leaves of all Phoenix's have what are called acanthaphiles [sp?] Which are basically leaflets that are adapted to be spines down in the core. Super hazardous for anybody working in a Canary Island Date Palm, or any date palm, but especially the canary. They can pierce your skin. They can pierce leather gloves. They can leave really nasty openings for infection. For some reason, the canary of all of all the Phoenix's leaves the worst possibility for infection. And so, within that very protected crown, birds and rats can be very happy. I know on Dolores you often hear like five different kinds of birds living up in the crown of a Canary Island Date Palm on the females. So, Phoenixes are dioecious, they're male and female on separate trees. And so, the ones that have dates, the ones that have fruit, the females are also a good source of food for the birds and for the rats as well.
Not that I'm aware of. So, palms defenses tend to be mechanical such as the spines and also the fiberousness of the foliage, the stem and the roots. So, most herbivores that take on palms are fairly specialized. The rabbit and the gopher are perhaps exceptions. But certainly, within the insect world, there's not a lot of aphids, for example, that really can take down a palm because their leaves are just so armored in their substance, not even just the organs of armature, but the fiber that constitutes the leaf. But I don't know of a case and you know, I'm not the expert on this stuff, but I haven't had any clients who've had problems with rats hurting the palm itself.
Yeah. Just to note, we are trying to capture via video, the questions on video. We definitely have had problems over the years with rat mites in the palms for people who are trimming them.
Because that had some serious itching.
Wow. That's heavy. Yeah.
We have one gentleman who it is a chronic problem for him.
Wow. And what prevention measures do you use?
I don't know if we had any, to be honest at that point. We didn't really have a solution for that. We were trying to trap the rats.
And how long does the infestation last on a human?
So, they don't live on your body, on your person. So, as soon as you shower you should have them washed off.
But you have all that allergic reaction.
Yeah, I would think maybe just washing. Can you wash off the crown to remove any nasty up there?
I mean, I think that it wouldn't hurt the plant particularly. I think, you know, it might be a temporary solution perhaps just drive out the population.
If you do that, you want to, you definitely want to do the washing before the trimming and best if you do it in the dry season. If you can.
Can you speak to like Phoenix as a host for like for instance if you have pine trees growing out of it?
So, Phoenix is super well adapted to our climate and part of that is its ability to draw moisture onto the trunk. You know, if you think about the architecture of palms, they're really good water catchers and in particular, Phoenix is adapted to capture fog because of its habitat, where it's from. And so not only does it do that with the crown, but it also like absorbs that moisture in the fiberous leaf bases that are, that are underneath the crown. So, the number of different epiphytes that grow in Phoenix canariansis is extraordinary. There's hardly another host for epiphytes that I can think of in our climate that matches a canary.
They seem to withstand them.
They do, although I, when I see big epiphytes like caprosma, like mirror plant, like pines--like there is some eucalyptus in some palms on the corner of Octavia and Market. I do think that there can be a problem with the roots managing to get their way all the way into the bud. And restricting the emergence of the new leaves. So, I think there is reason to remove big epiphytes. If it's just like, the usual small stuff, but if it's a big fat rooted tree or shrub like a caprosma, I've seen Coast Live Oak, you know, in a, yeah, a Canary Island crown. I think there is reason to remove or at least cut back regularly so that the growth isn't so vigorous and doesn't attack the crown itself. It's not like, the plant is trying to do that, you know, but it's not like the job of that, of that epiphyte to do that. But that risk does, I think exists. Yeah. The other thing I haven't addressed is, just in pruning I mentioned it's best not to prune green leaves.
When you prune a Canary, you must use a completely sterile blade. So, it's got to be a new blade out of the package, cauterized blade or a blade that's been in a 50/50 bleach solution for half an hour. And you've taken that bleach solution very far away from any plantings because of course that would kill any plant and you rinse that blade completely so that there's no more bleach on it. And you really do want to do a hand blade. It's very hard to fully, sanitize a chainsaw. It's a lot faster to use a chainsaw, but it can be a real problem. The other thing is some of the, you just don't want to bring down a dead Canary Island Date Palm that's died of fusarium or who knows what, with a chainsaw. And I've seen this done where every little bit of sawdust is a vector for this lethal disease.
And so, I mean, I don't, you know, it's just like I've seen it on the Embarcadero, I've seen it in Union Square. It's just a very bad idea. Is it is the perfect way to distribute a possible vector for the fungus that kills the other palm trees. So, that's another thing. And then upon planting, if you're planting palms out of a container, you don't want to manipulate the root ball. So, it's the opposite of what we think of when we're planning a woody tree or woody shrub. You want that container root ball to just slip right into the whole and backfill. There's no reason to manipulate the root ball and all you're doing is setting back the plant. Because what's going to happen is new roots are going to come from the base of the trunk and they're going to succeed that old root ball and find their way into the surrounding soil.
And upon planting, a crucial piece is to make sure to cover the base of the trunk. So again, unlike the way we're taught to plant woody trees and shrubs, you don't want roots exposed at the base of the trunk. You want to make sure that the base of the trunk, which is called the root initiations zone, is covered with soil. This is a particularly California piece of advice, because if I were in Florida, this would not be the same advice. But in California where we have nine months or three months or six months of drought, those roots just hit the dry air and stop. And when they're coming out in air, it's only the roots that hit the soil and can stay a little bit moist that are able to get themselves into the soil and start to support the new growth of that palm tree.
And you know, if it's two or three inches or even six inches, it's probably fine. You don't want to go really, you don't want to go more than six inches deeper. But if it's in the container and there aren't exposed roots you plant it at grade. If it's in the container and there are exposed roots, you just cover it with a mulch so that you can cover the base of the trunk. Now in planting a Giant Canary Island Date Palm that already has like a cone of aerial roots way up above the grade level, that's a different story. I mean, there are some Canaries on Delores that have 10, 15 feet of aerial roots. You're not going to bury that palm tree to that depth by any stretch of the imagination. But it wouldn't hurt that palm if you were to lay down two or three inches of mulch on top of the exposed roots just at the bottom of the trunk.
You know, of course you can transplant big palm trees. But even in that case, the remaining root ball, the part of the root ball that that comes with the tree should not be manipulated upon planting. And then in terms of media, it's surprisingly helpful too to use sand as your backfill. Again, contrary to the way we plant woody shrubs and trees, because the palm is going to need, as well, air rated a medium as possible for the development of those new roots. And because the branching process, leads to a finer and finer root tip, as it reaches, say, a clay layer, the plant is going to benefit from that well drained a porous sand medium. Plus, it's a lot easier to stabilize a palm tree in heavy, the heavy mineral medium of sand and you get much less compaction due to organic decomposition say in advance of the, of the roots developing, you know, to fill that space.
I have a question. Years ago, and I can't remember that which kind of palm it was. It was down on Mission. A big palm that was being planted down there that we were having problems with and we were dealing with Ken Allen. And one of his big recommendations was to have better inspections of the trees when they arrive as big trees, of the root balls. Can you say something about that?
In general, your transplant is going to be more successful with a bigger root ball on field dug plants. So, the larger a planting hole you can prepare in whatever project you're working on and the larger root ball you can spec, it's going to raise your prices on freight. But and it might raise your price on the plant too, but it's going to set you up for much better success in the long run. Now, those are Washingtonian Robustas, those are Mexican Fan Palms and I recall seeing what was implemented. There was-- do you remember the approach?
Well, I know that there were multiple problems. One of them was there was too small a box. It was above, you know, the [inaudible] was underneath the sidewalk. We went underneath and saw...
How little volume there was? Yeah.
So, that was part of the problem. And the other problem he said was just that they had been planted with like little smaller root balls for quality.
And he recommended better inspection.
And you know, sometimes it's worth it for the person choosing the plant to go to the farm where the plants are being dug, especially if you're planting a dozen or two dozen or whatever it might be. Again, it adds some expense on the upfront, but it reduces the headache in the long term. And I think if I recall correctly, I mean, I can, you know, they're, they're a little, it's almost like the grade was raised a little bit on the planting holes, on the wells. There was more volume added to the root ball for those Mexican Fan Palms. Now palms, again, they can go into these relatively small, root volumes into, into containers as long as they're maintained with sufficient moisture and fertilizer. So, fertilizing is the other topic. A lot of palms, like Queen Palms and the Chinese Windmill Palms could benefit from a regular fertilizing regime, March, June and September ahead of the warm season, to get the color better and probably increase the vigor of the plant.
But, you know, this is why you might choose a different species. You know, you can kind of opt out of that. At least in a non sand soil in San Francisco. In a sandy soil, I would always hope that we are able to fertilize just cause there's palms in general, like a little bit more fertilizer than a lot of other plants. So, the Washingtonian, the parajabajas, the brahajas they're not hungry for fertilizer particularly. But these Queen Palms, which I didn't show a photograph of, because I'm not super fond of them for San Francisco, and these Chinese Windmill Palms, which are better, are more easily used in San Francisco, they both like, a good fertilizing regime. And in a palm you want to have a sort of a medium to low phosphorus number and you want to make sure that your fertilizer has the micros, the full spectrum of micros, particularly magnesium and that will basically set you up for success if you're able to lay it down March, June, and September. You don't bother with the fourth quarter because of the temperatures and you know that time of year, most of the palms aren't really growing much.
I was just wondering, Jason, do you work with our landscape architects and landscape designers?
I am in discussion with them. Yeah.
They installed about 16 Queen Palms, where I work at general hospital, and then what's the news on the new ones on Embarcadero?
So, that's a great area to grow Queen Palms. And they look to, to be planted bare root. I don't know. I didn't watch the installation process on those. They are very elongated and they look like they're grown in a particularly hot climate and an in a dense planting, originally. I do not know. I have no idea where they were sourced from. Bauman doesn't return our calls. Because we're really persnickety. We get in there and we say, look, "this is going to be better if you do it this way or if you select this crop versus that crop." You know, those Queen Palms are a good choice for the design and for the micro-climate of San Francisco. I would like to have seen them planted at a very small size from a 25 gallon, because Queen Palms are rather narrow when they're young and just with a sort of a regular pruning of lower leaves, you would quickly have tree like Queen Palms say in 10 years you'd have palm trees.
But the choice based on whatever regulations about the view shed, or the, the driver's safety and pedestrian safety was to have big, tall trees. So, but yeah, the fertilizing will help, you know, and again, Queens they're hungry.
So do you have any recommendation for[inaudible] palms, like sheet metal [inaudible]
The metal sheath is a good option and here in the botanic garden we have trouble with squirrels. They live in the crowns or they chew the buds of the Necal Palms that I showed you a lot of. And I would like to see a cuff, a metal cuff, or a smooth cuff used on the trunks of those palms that aren't touching the crowns of the other trees. Because, obviously once they're close enough for the squirrels to leap over. Same with the rats. It's not worth bothering on a palm that is like touching another tree or close enough to another tree. But if they're on their own, if they're separated from each other, those cuffs would be helpful I think in reducing rats and other animals that run up from the ground.
You got [inaudible]
I don't think so, because you just want to have them high enough off the ground that they can't be vandalized and low enough from the crown that the rodent or animal can't cross it because it's too smooth. So, it just needs to be the, you know, the length required to prevent a rat from making it across, you know, on the way up. But I don't have any expertise in it. It's purely just observation on my part. I've never installed one. I couldn't tell you where to get one. Yeah.
You have some healthy scenario palms right now? is there a way to compliment that?
Yeah. Perfect. Pruning hygiene above all, making sure that you use sterile handsaws for pruning. I think it's worth pruning, you know, for removing leaves that might fall for, for taking away a spore bed for other fungal diseases that might be like chronic, like the gliocalidium. Gliocalidium affects--the pink rot affects Canary Island Date Palms. They almost always grow out of it, but it leads to years and years of a, you know, unpleasant looking crown. So, I imagine that if you're removing dead leaves, you're reducing the source of fungal infection on that plant. But you're also improving safety because they're, you know, they're spiny when they hang and fall.
And then, you know, Canary Island Date Palms are quite drought tolerant in San Francisco. So, not letting, like if they're in a lawn or if they're getting a lot of water, if you can possibly dial down the water, it's probably better for the palm. And then, I think removing those big woody epiphytes. So, like the gum trees that are in the--the ones at Market and Octavia, the oak trees, the pine trees, maybe the mirror plant. I think that's just beneficial in the long run to prevent the possibility that those would grow into the bud and restrict the bud.
I actually had one. We have biodiversity goals now in the city it sounded from your talk like the Mexican Blue Palm, so I guess it has the most associations with native plants.
The Guadalupe Palm. So, the the Mexican Blue Palm is also from near California and it's from Baja. The Guadalupe Palm grows with California native plants with the requirements of California native plants. So, if you look at the grove in the southwest corner of Dolores Park, you'll see that where the lawn sprinklers used to hit the trunks, there are cavities, they look deformed, they're not happy. And then above the point where the lawn sprinklers used to hit the trunks, the trunks are perfectly fine. It's an indicator to me their natural inclination to grow in a more summer dry environment. They, I mean in habitat, they grow in many parts of the island or they used to before the goats ate them all. And one of those areas is underneath the canopy or with the canopies of trees that capture fog and drip it down all summer long. All the dry season long because down there the dry seasons like nine months.
I have seen like native bumble bees foraging on Guadalupe Palms in the nursery at Flora Grubb Gardens. You know, I like just, I've talked about this with other folks who are enthusiastic about California native plants as I am in San Francisco. You know, we've seen the Hooded Oriel building nests in our Washingtonian is in the nursery. We've seen mourning doves forming their nests on the palm leaf. Successfully, you know, fledging chicks on the Guadalupe Palm. The Guadalupe Palm is truly the sort of biogeographic native of California. You know, unfortunately that Desert Fan Palm is not, you know, it's from the Sonoran floristic province and it shows, because it just is not adapted to this cool humid coastal condition that we have. The Blue Palm, you know, it's more tolerant, but it's also from Sonoran floristic province. But any palm is going to be, well, most palms are going to be good sources of nectar and pollen for the generalists in our environment. Just as hummingbirds, will go to aloes, you know, when they're blooming. So, will other pollinators go to palm flowers? But palms also do in habitat have very specific pollinator relationships as well. Some are general, some are more specific.
Yeah, I don't think I need the mic. Plant sale at Merritt College this week at Merritt College in Oakland, 12500 Campus Drive. Saturday 9 to 3, there will be lots of plants. There will be music. I'll be selling copies of my book, "Weeds of the Urban Landscape." On Sunday it is 12 to 3 to sell the remaining plants only.
And that's the place you want to go. That's like rarefied plants. Some really interesting plants at Merritt College. Very cool stuff.
Any other questions?
I should plug my book before I go. This is my book. You can get it at Flora Grubb Gardens. You can get it on Amazon. If you want to follow me to my car, I'll sell you one out of the back of my car. But I, it's got a, you know, I can praise the photographs above all because I didn't do them. Caitlin Atkinson took the photographs. They're very beautiful. But I hope that the, because it's written from a San Francisco perspective, there's a lot of information in here that relates to west coast cultivation of palms, but there's also plenty of information about tropical palms, which is obviously where most palms grow. So, I guess the last, you know, the palm family runs from as far north as the Italian Riviera as far as south as New Zealand way deep in the South Pacific. There's plenty of palms for us in our landscaping region. They're just super unusual at this stage, and I'd love to see greater diversity so that we, you know, we can actually employ this unusual group of plants, in more beneficial ways for the landscape. So, thanks so much for your attention and time today. [applause]
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