Green Hawthorn

I was in my old neighborhood in the Lower East Side yesterday and saw a row of trees from across the street. I thought they may have been hawthorns, though was doubtful. It would seem like they would have been long past blooming this late in the spring. But sure enough, I found the entire block of Stanton Street was planted with Crataegus viridis or green hawthorn.


As you can see from the photo below, the bloom has dulled a bit and I'm sure these specimens looked much better a week ago. But I've wanted to blog about this plant for so long and have yet to get around to it so I'm not going to wait a whole other year!



Crataegus viridis is a small ornamental flowering tree with corymbs of white flowers in mid spring. The flowers are not as showy or colorful as a Malus or Prunus but they are quite lovely. And hawthorns have several other advantages to offer. Namely, depending on the cultivar, the plant is laden with showy, persistent berries in the fall and winter. 'Winter King' has long been a favorite due to it's gorgeous fruit set each year.

New leaves are quite different in shape
than the more mature ones.

Another advantage is this plant's status as a native to the southeastern US. Perhaps related to this, the plant is very tough and is not prone to the many diseases that haunt crabapples.

The bark is somewhat fibrous looking,
with longer vertical splits.

Finally, hawthorns provide habitat to many local wildlife species. The berries provide food for birds and the plant itself is a great supporter of butterflies. In fact, wikipedia has a great list of butterfly and moth species that find sustenance from this tree. However, one species that does not like the hawthorn is deer. Which is another terrific advantage. For the most part, deer avoid foraging on this tree, unless they are really, really hungry.



This could have something to do with the large thorns on the tree as well. The one above is a new thorn, but as they age, they harden into sharp, woody needles. I was on a job site at the zoo once and (not prepared, and wearing the wrong type of shoe) a needle went clear through the sole of my shoe and into my heel. It hurt. A lot.



Hawthorns are named as such because one definition of "haw" is "fruit". It can also mean hedge and in England Crataegus monogyna is often used as a hedge. Crataegus itself is derivative of the Greek work 'kratos' which means 'strength'. The origin refers to the hardness of hawthorn wood.

Monkey Pod Tree

I mentioned Albizia saman in last week's post about Asplenium and then promised to comment more on this lovely tree in the future. Well, that time is now.


First of all, what a beauty, eh? I am *in love* with the elegant, almost overreaching canopy. The form is so striking and, as common as this tree is in Oahu, I think I will always equate monkey pod tree with my wanderings on this trip.



Not that Albizia saman is native to the Hawaiian islands, it's instead native to Central and South America, distributed between Mexico and Brazil. Indeed, due to the region's geologic history, Hawaii is fairly sparse in terms of native plants. More often that not, the plants that are most popular here are native to other areas and were planted by colonists or passers-through. (Somewhat relevant to this information, in last week's post about breadfruit my friend Matthew asked if Artocarpus was endemic to Hawaii and it's not. It's native to the Malay peninsula and the surrounding islands.)



Here above is another shot of the tree pictured at the top of this post. You can gauge from the Monstera leaves below how big this trunk is. I'd say its diameter was probably around 9-10'. A woman at the Waimea Botanical Garden says the arborists speculate this specimen is over 200 years old. In that case it is quite like the "Samán de Güere" a Venezuelan national treasure and landmark. That specimen was originally recorded by Alexander von Humboldt, a German naturalist and one of the founders of biogeography, in his trip to South America between 1799 and 1804. You can see an old print of this Venezuelan icon here. Unfortunately, there's scant information about this tree online, in English (and my Spanish is pretty shoddy these days).



I know I'm quite smitten with a new species when I have a ton of photos of the feature I like so much (in this case, the branching habit) and one cursory shot of another key characteristic (in this case, the leaves). In fact, I was relieved to find I had even one picture of the species' pinnately compound leaves. Knowing that the leaves are pinnately compound, you could hazard a guess that Albizia is a member of the pea or legume family, and you'd be right. Technically these days, you'd say it is a member of the Fabaceae family, though Leguminosae is still commonly used and considered acceptable. In either case, Fabaceae trees have similar leaves and pea-pod like fruits. Other species of this family which we have previously discussed are Gleditsia, Robinia, Sophora, Lupinus, Cercis and Cladrastis.



Finally, on a very unscientific note, every time I look at this photo, I can hear Meryl Streep saying in her Danish accent "I had a farm in Africa." Indeed, monkey pod tree is related to Albizia amara, a tree that is found in the dry scrublands between Sudan and South Africa.

Traveler's Palm

This recent trip turned me around when it comes to Ravenala madagascariensis, or traveler's palm. Previously, I had kinda pooh-poohed it. The form is just so...unnatural for a tree. People always seem to plant them because they like the flat rigid form then are dismayed when they see the wind shred the leaves to tatters. It always seemed a bit...gimmicky.



And if I had only encountered this plant in Waikiki then I think my opinion would remain unchanged. But luckily I went to the north shore for some vacation time after my site work and stumbled upon the Waimea Valley Botanical Garden. I was going to Waimea valley primarily to seek out the waterfall, so imagine my delight when I saw there were thousands of plants, all with labels.


I can only imagine how difficult it is to maintain a garden in a jungle valley and sure enough the landscape of the Waimea Valley Botanical Garden is sprawling and a bit shaggy. Personally, I preferred that; it would just seem wrong for a tailored garden to appear in a site like this. And I especially liked encountering this massive clump of traveler's palm growing alongside a path. It reminded me of the many people who have sought fresh water in the crevices of the leaves while on long, isolating treks (indeed, this is why the plant is called traveler's palm). Someday, when I have my Hawaiian villa, I think I will grow a few traveler's palms and let them run wild, clumping into an almost unmanageable grove.


Despite the use of "palm" in the common name, Ravenala madagascariensis is actually more closely related to bird-of-paradise (Strelitzia reginae) than any true palm. The flowers are similar too, though Strelitzia's blossoms are more colorful and a bit 'neater' looking.



Finally, as the species name would imply, this plant is not only native to Madagascar but is endemic to the island. It is not found in the wild anywhere else. In fact, many posit that the traveler's palm and one of its pollinators, the ruffled lemur co-evolved. This is likely based on the shape and size of the lemurs muzzle and the Ravenala's blossom.

Daffodil Season

It seems downright insane that I have yet to blog about daffodils - at least not in any substantial manner. I mean, I'd say pretty much anyone with the most remedial plant knowledge would know a daffodil -- and most of those people would probably say they liked them, too, right? I mean, who doesn't like a daffodil?


The above is outside of Lewisohn Hall - the building that houses my department at Columbia. I have begun many first-day-of-class introductions outside that doorway and the red oak (Quercus rubra) you see in the courtyard is always featured as one of the first trees students will learn. The planting area looks pretty nifty right now, with hundreds of cyclamineus-type daffodils in bloom.



So. "Cyclamineus-type" daffodils -- what's that? Daffodils (or Narcissus) are classified into twelve (actually now, according to the American Daffodil Society, there are thirteen) divisions. Cycalmineus is one of the divisions and refers to the windswept or Cyclamen-like flowers.


Other divisions are named for the size of the flower's cup (the tubular part of the flower, technically called a corona) relative to the size of the floral leaves (or perianth). Both the flowers above and below have cups that are more than 1/3 the lengh of a petal, but don't exceed the petal's length, which means they are large cup division daffodils.


(By the way, even people who don't like bright yellow in the garden, can still have daffodils like the one above.)

If the cup was larger than the floral leaves (or if we want to be non-technical, the petals) they would be trumpet-type daffodils.



Other divisions include small cup, double-flowering, triandrus (or 'weeping'), jonquilas - which are small, fragrant and have one to three flowers per stem, tazettas (paperwhites), bulbocodiums - which have a very, very large cup and insignificant perianth, split-cupped (where as the name suggests, the corona is split into a 'second row' of petals), and division 12, which is a catch-all for types that don't fit in other categories. The ADS added the 13th division for wild, unhybridized types.


Lastly, I saved division 9 for last, since it's a favorite. They are the poeticus type daffodils, characterized by the extremely white perianth and small crinkled orange cup. Usually the cup is yellow with red trim. (I'll admit, this cup looks big for a poeticus and it could be a small cup type, but you get the idea. The true poeticus types are dashing.)

PS: I think we all know the story of Narcissus and his, well, narcissism. What I don't know is the story behind the common name daffodil - where that word came from. If anyone knows, please comment!

Orchids

Here's the last few shots of some beautiful hybrid orchids from Adore Florist in Noho. Most plant enthusiasts probably know that the orchid family, orchidaceae, is the largest family of flowering plants. There are, approximately, 880 genera and 22,000 species of orchid.



I'm guessing that these beautiful fuchsia stems are hybrids of the Vanda orchids, as Vandas may have magenta flowers, take easily to hybridization, and are popular among florists. But with all those genera to chose from, I'm only hazarding a guess. I love orchids, but only as much as the next person. Someday, when I live elsewhere than New York City (and thus have light and can avoid the searingly dry heat that comes with steam-powered radiators every winter) I will experiment further with orchid care. For now, I'm focused on keeping spider plants and sanseveria alive.



When I was a kid living in Malaysia, we had orchids - mostly Oncidiums, I think - growing in the trees of our yard. Like most of the orchids in subtropical or tropical regions, these plants were epiphytes; that is, they lived in the canopies of trees, benefitting from the canopy's microclimate without detriment to the host tree (just like the previously-mentioned Spanish moss).



Orchids in temperate regions are usually terrestrial, so New York natives like Platanthera and Spiranthes appear quite different from the orchids we see in flower shops. What groups such seemingly different looking plants into Orchidaceae are several characteristics: they are monocots (more primitive flowering plants that exhibit parallel veins); they have one modified petal that's called a lip or labellum; and finally, the reproductive parts of the orchid's flower are fused into one column (similar to, but different from the staminal columns of, for instance, Hibiscus).

Plumbago auriculata

While we New Yorkers can rest a little more easily now that the snowstorm has passed (and we really weren't hit too badly at all; apologies to those of you snowed in further south!), there's still scant plant material to observe. So...I'm posting today about a plant in our office, Plumbago auriculata.


Plumbago is native to south Africa but is a common site in California and other Mediterranean climates. It's a vigorous grower and blooms as long as it has full sun and warm temperatures. Ours here, overlooking Crosby Street, would never live outside but the southern exposure has kept it blooming since December.


On a hunch, I checked to see if plumbago was related to phlox or vinca, since the flowers look so similar. No such luck; all three plants belong to different families (Plumbaginaceae, Apocynaceae and Polemoniaceae, respectively).


See below the fibers that protrude from the calyx? Those sticky fibers (commonly referred to as glandular hairs, though technically they are too substantial to be simply hairs) will remain at the base of the flower (look to the far right) and when a seed is ready for germination, they may attach to any animal that happens to pass by the plant. To be sure, I've seen more than a few plumbago seed capsules stuck in my boss's hair after she's watered this plant. These hairs also secrete a mucilage that can trap and kill insects.



The name plumbago is derivative from the Latin word for lead, plumbum. That's because it's believed this plant can cure lead poisoning. The plant is believed to also be a remedy for warts, broken bones and wounds. Indeed, hardy plumbago (Ceratostigma plumbaginoides) is commonly called leadwort.

Elder

Perhaps my camera should break every January. I mean, really: who wants to look at dreary photos of plants in a bleak, wintry landscape when we can reminisce about warmer days?

Like the day in May that I took this photo of Sambucus nigra, or elder, or elderberry, growing in the Liz Christy Garden:


The flowers are beautiful, creamy white corymbs. Corymbs are flat-topped flower structures. The most popular flower structure of course (after the simple flower), is the panicle, which is a cone-shaped flower. Paniculata is a popular species name as it refers to this flower shape. Other flower structures include racemes, spikes, catkins, spadices, and umbels.


The flowers and the black-colored (thus, S. "nigra") elderberries that follow are non-toxic, however the rest of the plant is poisonous if ingested raw in high quantities. When processed into a syrup, the plant has been proven to reduce some cold and flu symptoms. But, don't try that at home, kids.

The flowers are used in drinks such as an elderflower cordial and the equally-obviously named Sambuca. The berries, like many others, are used in jams and jellies.

Callicarpa and Penn Station (the good one)

It's always a good bet that when you see a plant full of untouched fruit in the winter, that said plant is not native. The subtext is that the non-native fruit is undesirable to the native wildlife. Things get a little muddy when you consider that some of our local wildlife is also non-native, or that deer -- a native animal -- will eat almost anything. But the concept has some merit, and if you assume the plant below is a non-native, you'd be right.



Here comes the part where I have to admit to a previous mistake (I hate that). When I last spoke about this genus, Callicarpa, I showed photos and equivocated on the species. I suggested it could be Callicarpa dichotoma or Callicarpa japonica and then I favored the latter.



Seeing these specimens at the NYBG last week, it's clear that the plant I posted on in September 2008 was Callicarpa dichotoma and this plant is C. japonica. The fruit set is decidedly different, the latter plant has fruit and flowers borne on longer cymes whereas the former has fruit set closely to the stem of the plant. Cymes, if you recall the post about linden flowers, are the small stems that connect the flower (or fruit) to the twig. Mea culpa.

Onward, to some fun models. The building below is a new addition to the NYBG train show but chances are it's a familiar building to most New Yorkers. Its familiarity is not because we see the building depicted in movies or postcards, but sadly because it was a beautiful building that the city foolishly demolished.


As you can see from the hand in the left of the photo, the model is massive. It's beautiful, too, though one has to look at some of the stunning black and white photos of the original structure to realize how lovely the building really was.



The model makers, as you can see, were very detailed. Though that man is evidently very, very tall.



Note the acorn cap on the column!

Christmas Rose & the Guggenheim

Recently the New York Botanical Garden invited me (or more accurately, they invited New York Plants & Other Stuff) to a sneak peak of their holiday train show.

If you haven't been, definitely check it out. I had been once before in 2003, but forgot how much fun it is to see these models of New York City sights made out of plant material. Paul Busse, a landscape architect and principal of his firm Applied Imagination, fashions hundreds of buildings, using only bark, seeds, petals and leaves, etc.. He even uses lichens. To wit, one of my favorites had to be the Guggenheim:


Of course, I also had to walk around the grounds and check out what was happening in the garden. Helleborus niger or Christmas rose or black hellebore, immediately caught my eye. Like Lenten rose, Christmas rose is named such due to the season in which it blooms. The common name black hellebore is applied becuase the rhizome (a long, flat tuber or bulb-like
structure) is black.


The flower structure you see above is a bit unusual. The white parts that look like petals are sepals. The larger, stringy yellow parts that look like stamens are actually nectaries, petals that have been modified to hold nectar. Pollinators are usually bees and flies.


Hellebores have a rich history of medicinal use. The plant's roots contain two chemicals, helleborein - which can be considered a cardiac poison, and helleborin, a narcotic posion. Highly toxic, the plant can be used as an emmenagogue, cathartic, diuretic or cardiac stimulant in low doses. Higher concentrations of Helleborus niger can cause death allegedly by relentless spasms and exhaustion. Wow, right? Apparently in ye olden times the plant was used to treat such outdated afflictions as hysteria, insanity and my new favorite word: dropsy, which is sort of like an extreme bloatedness.

Next week I'll be posting more photos of Busse's models along with some new plants.

Agave Americana

When I posted about Brugmansia I mentioned that the horticulturist at Central Park Zoo likes to experiment with marginally hardy plant materials. Agave americana is another plant in this category.

Agave americana is also called century plant, because this plant only blooms every ten years or so, and we all like a little hyperbole. When the plant does bloom it sends a very tall stalk into the air, high enough above the ground to protect the blossom from terrestrial predators. After the plant blooms, it dies.

If one were to cut the bloom's stem before the flower had opened, one could collect a sap - called agua miel (honey water) - ferment it and create a drink called pulque. Agave americana's cousin, Agave tequilana is of course responsible for a drink called tequila.

Cherries

I inevitably overlook cherry trees (Prunus sp.). I don't know why. In the spring, I look forward to the crabapples, but then am always insensibly surprised by how beautiful cherries are in the spring.

I've mentioned them in passing once and mused on the poor use of the potentially beautiful weeping variety, but I've never acknowledged the lovely fall color they have.


The above is taken outside of the Stuyvesant town apartments - but all around the city I have noticed how lovely cherries look this time of year. The fiery oranges and sunburst yellows contrast well with the trees' dark bark and the evergreen Pachysandra beneath.


Cherries area always easy to spot, even in the winter. They are a coarse-limbed tree with a dark brown - almost black - bark with a rosy pink undertone. Of course, more notable than the color is the bark's smoothness, punctuated with lenticels. (Lenticels are specialized 'pores' in the bark that aid in gas exchange.) The easy way to describe cherry bark is to say it looks like Shantung or raw silk.



But if you weren't convinced you had encountered a cherry, and the leaves were still on the tree, you could look for the small 'pimple' at the base of the leaf's petiole. That is typical to Prunus.




I haven't used a species name in this post, primarily because cherries are so often hybridized. This plant is most likely a Prunus serrulata, but it could be a hybrid of several species.

Norway Maple

These are some exquisite specimens of Norway maple (or Acer platanoides) growing in the cemetery at Old St. Patrick's Cathedral, in Nolita.

For those of you who don't live in New York City, I cannot impress upon you how rare it is to see a huge, spreading maple tree outside of Central Park. The walled cemetery has protected these trees well.


A couple weeks ago, we looked at sugar maples which, at first glance, can seem quite similar to Norway maples. The margins are entire, but Acer platanoides leaves are usually much larger, change color later in the season and change to a yellow hue, whereas Acer saccharum leaves are smaller and can turn yellow, orange and red.

The other undeniable difference between the two maples is in the leaf's petiole. Snap a leaf off a branch of the Norway maple and you will find the exuding sap is white. The sap on a sugar maple runs clear.



Here's a shot through the keyhole of the cemetery doors.

If we got a bit closer to the trees' trunks, we may find that the grass is not growing as vigorously. That's because Norway maples are allelopathic. Allelopathy (or more specifically, negative allelopathy) is a phenomenon where the maple can produce chemicals that limit the growth of other plants in its rootzone. For this reason, the non-native Norway maple is deemed invasive. Plants cannot grow beneath its canopy and thus the plant has more opportunity to spread. The dense shade of this larger-leaved maple amplifies this situation. I discourage students from utilizing this plant for these reasons.




Finally, though, I'll end on a light note. I've mentioned my aunt before, and that I tinker in her garden a bit. She has a large red-leaved cultivar of Norway maple in her front yard. When she bemoans the sad state of her lawn I remind her that the maple isn't helping things and she feels better. A couple months after we discussed this, she brought it up again and called the tree her Norwegian maple. Nowegian Wood, I get. Norwegian maple...not so much!

Halesia tetraptera

Since the last few posts have been about Central Park Zoo, I'll stay there for a bit longer, at least to talk about Halesia tetraptera, or Carolina silverbell.

Carolina silverbell is a small understory flowering tree that can ultimately reach a size of 30-40 feet (there's a larger one on the north side of Central Park bandshell, too). It has a lemony fall color that is evident in these photos, and in mid-spring the plant is covered with white bell-shaped flowers.

But today, and even after the leaves have fallen, the notable characteristic that remains is the seedpods. Tetraptera literally means four-winged and refers to the four flattened corners of the seedpod. Halesia is named for a botanist, Stephen Hales.

Sugar Maple and a Brief Explanation of Fall Color

When it comes to fall color, the sugar maple (Acer saccharum) may be king.



This specimen is turning yellow, but you can find sugar maples turn fiery orange and red as well.

A commenter asked earlier this week why leaves turn different colors in the fall, and now I'm going to attempt to answer in just a few short sentences....


Most people know that chlorophyll is the chemical compound in plants that is necessary for photosynthesis (the production of sugars and carbon dioxide in a plant). Chlorophyll is also a pigment that absorbs the blue and yellow colors from sunlight, making plants appear green. The more chlorophyll in a plant, the more green it appears (and also, the more energy it produces and in some cases, the faster it grows -- it's generally why green-leaved plants grow faster than their variegated counterparts).

In the fall - as the days become shorter and colder - a membrane grows between the twig and the leaf petiole which clogs up the flow of sugars and water between the leaf and the rest of the tree. This eventually prevents the chlorophyll from being productive and the compound breaks down.

That's where carotenes and anthocyanins - two other pigments in leaves - come in to play. These pigments exist in the leaf all year, but are overpowered by the presence of chlorophyll until autumn. The former absorbs blue-green and blue light, which means that the presence of carotene - once the chlorophyll is gone - can make a leaf look yellow. Anthocyanins absorb blue, blue-green and green light, which makes a leaf appear red. The amount of anthocyanins and carotene varies among species (and in the case of sugar maples, they vary among individual plants).


So now, when you see a tree that has yellow fall color, you can impress your friends by observing that said tree must have a high concentration of carotene. I'm sure they'll be fascinated!

Back to sugar maples, briefly. Sugar maples of course are responsible for maple syrup and, as the common name would imply, the tree's sap is quite sweet. They are also very hard-wooded trees and the lumber is used for basketball court floors, pool cues and bowling pins.

My students struggle with discerning differences between sugar, silver, Norway and red maples. I'll post some of these other species in the days to come. The important characteristics to look for in sugar maples are a smooth or entire leaf margin and furrowed bark. While Norway maples also have entire margins, their bark is more stripey (and the leaf petiole exudes a white milky substance). Unlike sugar maples, red maples have serrated edges and silver maples have deep leaf sinuses.

Acer comes from a Latin word for sharp - referring to the hard wood, which could be utilized to make spears. Saccharum means 'sugar' - like saccharine.