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.

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.

Yellowwood

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.

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.