Thursday, October 29, 2009

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.

Wednesday, October 28, 2009

Grape Leaf Anemones

Over the years of working in high-end residential design, certain perennials have consistently been used - earning a loyalty from designers due to their long period of flowers, the heartiness (and hardiness) and simple beauty. Anemone tomentosa 'Robustissima' is definitely among that group.

It can start to bloom as early as August and lasts well into November. It's an elegant perennial with soft pink or white blossoms and foliage that, as the common name indicates, looks a bit like grape leaves.

Anemone is from the Greek word for wind, anemos - legend has it that anemone flowers sprouted from the tears wept by Aphrodite after the death of Adonis. Of course, I think that story would refer more to Anemone blanda, or windflower, which is a bulb native to Greece.

Monday, October 26, 2009


Autumn really is a wonderful time of year for tree watching. Not just for the aesthetic pleasure of seeing various trees' leaves change from green to yellow, orange or red, but also because while this change is taking place, different trees will begin to reveal themselves to you.

For instance, the entry to Central Park near the 5th Avenue stop on the NR train has never slowed my pace very much. If I enter the park here, I usually rush down to the nearby pond (the one where we saw our friend taking a dip last August) and then begin to meander through the landscape.

But on Saturday, this yellow tree caught my eye before I'd even entered the park.

When I neared the tree I quickly realized it was yellowwood (or Cladrastis kentukea, or C. lutea). I was delighted. I love this tree, but until now I have only been able to show students a smallish specimen near the magnolias behind the Met, or the larger one in Jefferson Market Garden.

Yellowwood are fairly easy to identify. They have a pinnately compound leaf with leaflets quite larger than a honey locust, sophora or black locust. More specifically, the terminal leaflet is always broader in shape than the lateral leaflets. It is almost spatula-shaped, where the lateral ones are simple footballs.

Like those other trees with pinnately compound leaves, Cladrastis is in the Fabaceae or pea family (also considered the Leguminosae family). And, like other members of that family, the tree has long, pendulous sweetpea-like flowers in the late spring.

The bark is gray and smooth. If one were to trim a branch and look at the cut, they would see yellow heartwood, thus the common name.

Cladrastis comes from the Greek words klados (branch) and thraustos (fragile). clearly refers to a native range. The other species name, lutea, means yellow.

Thursday, October 22, 2009

Beach Conifers

I went to the Jersey shore last weekend with the hopes of getting some surfing in before the water got really cold. Alas, a quick look at the ocean confirmed my fears that the stormy weather had rendered the waves unsurfable.

So instead, I took a long walk and got some photos of plants that are typical to a beach location in the mid-Atlantic. I'll post a few more shots next week as I wait for the Manhattan fall color to really queue up. Today, we'll look at a few conifers.

Above you can see a small Juniperus virginiana, or eastern redcedar, in the foreground and a larger one further back. Redcedars aren't expressly dune plants but instead are considered colonial or pioneer plants. Their seeds are often deposited by birds in disturbed or nutrient-poor landscapes like sand dunes and the edges of highways. The saplings survive the tough conditions and provide habitat for more birds and small mammals, which in turn brings more plant diversity. (That's a very abridged version of an aspect of forest succession.)

Like other junipers, this plant has the distinctively aromatic berries which will immediately remind some of you of gin. Many mistakenly believe gin is made from these berries, but instead gin is a grain alcohol that is flavored with the berries.

Junipers can be tough to ID if no berries are present; one could confuse a juniper with a Thuja, Chamaecyparis or Cupressus, to name a few. But, a close look at the branchlet (in this case a leaf is one individual scale, what's in my hand above is called a branchlet), shows that junipers have two different leaf types. The juvenile leaf, found at the terminal tip of the branchlet, is spikier and has a sharp tip that points away from the stem. Mature leaves are flattened down against the stem -- these are the leaves nearer to my fingers. The presence of these juvenile and mature leaves are a great way to confirm that the plant you see is Juniperus.

Another plant you often find on the beach is Pinus thunbergii, or Japanese black pine. A non-native, this plant is often encountered on beaches due to its high tolerance to salt spray and its evident low requirement for nutrients.

Pinus thunbergii's needles are stiff and smooth, found in fascicles of two. While the specimen above is fairly symmetrical, as this tree ages it can achieve a gnarled sculptural appearance due to the pruning affect of the wind.

Wednesday, October 21, 2009

Book Review: Shade Gardening

A former student wrote me yesterday, mentioning my post about plants for beachy locations, and asked me if I could recommend a few books for shade gardening. I can.

I really like Ken Druse's Natural Shade Garden because it includes actual information about shade-loving plants in addition to images and discussion of good plant combinations. The photos are enchanting and plants are named in the captions.

Similar to the Druse book is Keith Wiley's Shade. This is a slightly slimmer book, and though I prefer the images in the Druse book, Shade has a great glossary of plants in the back for easy reference.

Both the above books draw inspiration from woodlands - as the plants that naturally occur in woodlands are tolerant of shade. And of course, woodlands (or most of them) are only really in shade after the canopy leafs out and until the leaves fall in autumn. A great book on woodland plants is Beth Chatto's Shade Garden.

Monday, October 19, 2009

November Vogue

October seems to be a big month for me as far as publications go. In addition to last week's article about the Anne Frank Center, this month's Vogue includes a profile of my boss, by Hamish Bowles. The article is a great snapshot of her design philosophy and may give readers a better idea of what kind of work I do.

I'm mostly excited about this because the illustration of the garden site plan was rendered by me!

Scans of the complete article follow below, in case you'd like to read it.

Friday, October 16, 2009

Anne Frank and the Horsechestnut

Being an avid plantswoman, friends and family send me LOTS of articles and links about trees. I welcome them all and read most of them.

Last April, my sister sent me this brief article in the Times about the horsechestnut tree which resides behind the annex where Anne Frank, her family, the van Pels family and Dr. Pfeffer hid from the Nazis. The Anne Frank Center in New York City, literally three blocks from my office, was preparing to award ten horsechestnut saplings - progeny from the very tree Anne Frank gazed upon - to various institutions in the United States.

Anne Frank's story and diary resonated strongly with me as a young person, and when I saw a, well, a branch between plants and her story, I was motivated to reach out to the Anne Frank Center and volunteer any services they may need.

Using experience I acquired from writing and reviewing RFPs for the City Planning Department and the Wildlife Conservation Society, I worked with Yvonne Simons and other staff at the Center in preparing a Request for Proposals that would be sent to institutions interested in obtaining a tree. I also was a member of the committee that reviewed the proposals and ultimately selected the institutions which will receive the saplings.

You can read an article in today's New York Times about the selected institutions here.

All of the proposals were touching and selection was difficult. Central High School in Little Rock, Arkansas will receive a tree, as will the Southern Cayuga Central School District in upstate New York. The thought that schoolchildren -- Anne's would-be peers -- will care for these trees is profoundly moving to me. Boston will receive a tree because a little girl heard about the RFP and wrote a letter to the mayor. It's another story about how a young person is capable of making a meaningful contribution to his or her society, despite their youth, inexperience or in Anne's case, the bigotry or hatred of their times.

And of course, the fact that these trees are revered and sought-after demonstrates how important nature is to us, emotionally. Perhaps Anne puts it best:

“From my favorite spot on the floor I look up at the blue sky and the bare chestnut tree, on whose branches little raindrops shine, appearing like silver, and at the seagulls and other birds as they glide on the wind.” She adds, “When I looked outside right into the depth of nature and God...then I was happy, really happy.”

Wednesday, October 14, 2009

Southern Live Oak

When my parents told me they'd be spending Columbus Day weekend in Savannah and Hilton Head, I was happy for them, to be sure. But I may not have expressed that adequately, as my first response was a bit self-centered: "Will you take some pictures of the live oaks for me?!"

I've seen the southern live oak, Quercus virginiana before - after all I did go to grad school in Georgia. But, unfortunately, my photos - taken on a trip to Savannah in 1999 - aren't digital, so I issued speedy instructions to mom and dad to shoot away.

I'm hard-pressed to name another tree that is more picturesque than the southern live oak. Its open, vase-shaped habit is stunning, especially when planted in allees. Add to that, the trees have this great, lazy lean to them like the one below. It really does remind you of the south: long, hot summer days, mint juleps and Tennessee Williams. ...Well, it can remind me of those things!

Of course, the other characteristic that makes the southern live oak so remarkably beautiful isn't technically part of the tree at all, it's the Spanish moss that cascades from the trees' branches, swaying so slightly in the warm breeze.

Spanish moss, or Tillandsia usneoides, is an epiphyte - which means that it grows on another living plant. Epiphytes are similar to parasites in the fact that they rely on other living things for sustenance, but parasites ultimately damage the host organism, whereas an epiphyte can 'live in peace' with the host.

Friday, October 9, 2009

Ceiba speciosa

When I first encountered this tree on my trip to Barcelona in April '07, I thought it was a baobab (Adansonia), though the climate was all wrong for it, and the specimens below hardly seemed likely to reach the massive size typical to that African tree. Also, baobabs don't typically have the thorns (technically "emergences") that this tree exhibits.

The tree isn't baobab - it's Ceiba speciosa, or silk floss tree, but they both belong to the same family, Bombaceae (kapok - another species of Ceiba - is also in this family). Ceiba is native to South America and typically has the bottle-shaped trunk you see above, as well as distinctive thorns. It can also tend to lean, thus meriting the common Spanish name of palo borracho, which means 'drunken tree.'

As forbidding as this tree looks when it's defoliated, they are quite striking when covered in pink blossoms.

Thursday, October 8, 2009

Stone Pine

I made brief mention of stone pine (Pinus pinea) in my earlier post of the Parc del Clot. Though it deserves greater mention in a post of its own.

Stone pine is native to northern Morocco but has been naturalized in the Mediterranean region for so long, many mistake it as indigenous. It's easily recognizable in such climates due to its long needles (in fascicles of two), orangey and plate-like bark and, most of all, it's striking habit.

A quick image search on google will reinforce the fact that this tree has a very consistent form - they branch high and have a flat-topped habit.

Above, a stone pine at the Getty Center.

Now the really tasty part: the stone pine is the tree that brings us the pine nut. So without this wonderful tree, we'd be without pesto and pignoli cookies. The tree's culinary value largely accounts for its cultivation beyond its native range.

Tuesday, October 6, 2009

Nouvel's Parc del Centre del Poblenou

Last week when I was discussing the Parc del Clot in Barcelona, I made a reference to the nearby Parc del Centre del Poblenou, designed by architect Jean Nouvel.

Nouvel is best known for his architecture. The Pritzker-Prize winning architect designed the new(ish) Musee de Quai Branly in Paris, and is known among the Barcelonans for his Torre Agbar.

As far as I know, the Parc del Centre del Poblenou - opened in April 2008 - is Nouvel's first foray into landscape design. If you, dear reader, will forgive a tiny bit of snark in this post, let me add that I hope it will be his last.

Don't get me wrong; I'm pretty sure what Nouvel did is precisely what many architects would do if designing a park. The entire park is surrounded by large walls, limiting pedestrian passage and creating a sense that one is somewhat 'trapped' in the park. Even the cut-outs that you can see above are inpenetrable to air and wind as they are filled with plexiglass. To Nouvel's credit, the walls were intended to block out noise from the nearby traffic. However, there are many other ways noise can be mitigated. Grades can be raised or lowered, berms can be built, or (without water restrictions) white noise can be introduced.

A strange theme you discover while walking through the spare landscape is Nouvel's insistence on training or manipulating plants. Vines are trailed over large arbors, as seen above (arbors which, puzzlingly enough, fail intersect sensibly with any other landscape element. ...Why, why is this axis not aligning with the gate, argh? Also: note to self - use heavier footing for area lighting fixtures!)

Above, plants are stacked in towers raising to the sky, and below, well, I'm not sure what those nets are for.

Visitors have little choice when it comes to seating. Metal chairs are secured to the ground with footings and the absence of lawn areas (understandable in a water-deficient climate) further eliminate opportunities for improvisation in the landscape. To me, that kind of improvisation is a crucial part of a park experience. I want to walk through a landscape, survey my environment, and pick a spot to sit down that is my own special nook. It's about discovery. The fact that the seating locations are predefined by Nouvel steals some magic away from the visitor.

And, well, not to nitpick, but weeping willows (Salix alba subsp. babylonica) in a water-poor climate makes no sense to me.

I will aquiesce that I liked the treatment of this road, which bisects the park. The Parthenocissus is quickly covering the arbors and the structure seems fitting for the roadway. And I did love the use of rebar in the grillework for the vines, below.

Landscape architects love to wring their hands in despair at the thought of architects taking some of our territory. But frankly it seems unnecessarily insecure. If anything, a park like this (and perhaps to a lesser degree Tschumi's Parc de la Villette) demonstrates how specialized a landscape architect's knowledge and sensibility are and how unique they are from the field of architecture.

I used the word magic earlier in this post (and also when I discussed Vaux le Vicomte), when describing a landscape experience, but that's unfair to the designer. There's nothing supernatural in Olmstead's or Le NĂ´tre's designs. The success of their work (and many others in our field) is the result of a lifetime of study and discipline in the unique field of landscape architecture.

Thursday, October 1, 2009

Parc del Clot, Barcelona

In 1986, the Parc del Clot was opened to the public in Barcelona. The park, designed by Daniel Freixas and Vicente Miranda, was built on the site of an old train station.

Though the park may not be a must-see destination (like Gaudi's Park Guell - more on that another day), there are some nice design gestures at play here.

First, you can see they left the remnants of the train station's adjacent factory buildings intact, in order to define separate outdoor rooms.

Of course, with the water restrictions typical to a Mediterranean clime, it was not suprising to see that this adorable (though strangely Colonial-Williamsburg-meets-the-Alhambra) pineapple fountain was not running.

Below, you can see that the Pinus pinea, or stone pines, are aligning with the remnant columns.

When I was at the park I didn't realize it was built on an old train station, so the emphasis on the linear path below -- which takes you from the more private, passive-use areas of the park to the more active area of playgrounds and basketball courts -- seemed like an overwrought gesture. I still think it's a bit heavy-handed, though it makes more sense to me now, as presumably you are walking on a long-defunct rail line.

I did like that these white arches also functioned as lights -- a band of lights run inside the frames, which must look quite pretty at night. It's also useful, as this park often has concerts and thus a lot of late night traffic.

Again, this park is not rewriting principles of landscape design, but has demonstrated its success with its visitorship. The park had people using all the resources the design provided - people were picnicking, playing sports, walking their dogs, using the playgrounds. It was a marked contrast to the new Jean Nouvel park that had opened a kilometer or two down the Aveniguda Diagonal. More on that park in the days to come.

Sidenote -- yes, it's been a long time since the "New York" part of my blog title has been relevant. I am planning on wrapping up with Barcelona/Paris in the next week or two, just in time for fall color!