A Cakewalk of a Treewalk II
Bill Long 9/13/08
Coaxing Knowledge from the Trees
We learned that it is best for the Deodar Cedar to have a thick canopy than "thinned" branches. Our guide didn't much like the several Ginkgo trees (Ginkgo biloba) in front of 1190 Hamilton Ave., Palo Alto. This caused a pleasant exchange, since many of us "nonprofessionals" love the tree. We like its antiquity and simplicity, the absolutely unique nature of the leaf, the "cleanness" of its appearance. It is great to be able to argue about trees; I would much rather discuss why someone likes or doesn't like a Gingko than why s/he likes McCain or Obama.
A new tree for me was a Podocarpus gracilior, which many people in the group knew as the "Podocarpus" (though it is popularly known as the "Fern Pine"). The latest classfication has it as Afrocarpus elongatus. The online Encyclopedia of Stanford Trees tells us not only where there are several exemplars in the Palo Alto area, but informs us about the "name change," too. Here is another picture of its 4'' narrow leaves, its most distinctive feature. The description on that page is worth quoting: "A graceful, sub-tropical tree from Kenya. Numerous thin, leathery leaflets on willowy branches." It became "well known" around the Stanford campus just before 1970. Most people think of that period as the days of radical politics; why not "reframe" that period as the triumph of the Podocarpus? The alternative name, Afrocarpus (since it originated in Kenya?) elongatus dates back to 1974. Just when the "Afro" as a hair-do was at its peak...
Continuing the Exploration
We came across a very popular tree--the Coast Live Oak (Quercus agrifolia). Here is a wonderful picture of the jagged leaves as well as the pointed acorns, clad in their little brown caps. The brochure produced by Canopy.org says that "nothing kills this tree except root damage." Yet, as this web page says, a new and dangerous disease has hit this kind of tree--called Sudden Oak Death. Well, we need to learn the Latin name of diseases as well as trees, don't we? It is called Phytophthora ramorum or, in translation, "Corruption or damage of branches." So significant is this problem, especially in the American West, that CA appointed an "Oak Mortality Task Force" in 2000 to study the problem and give advice on what to do about it. We also learned that the Bay Laurel tree, a prevalent CA tree is the "host" or "vector" for the organism that brings the sudden death. Here is a picture of the leaf/flower pattern of the Bay Laurel tree (Umbellularia californica), so that you now know what the culprit looks like...
When we arrived at the Red Horsechestnut (Aesculus x carnea), we not only saw this fertile hybrid tree (though its hybrid character was not emphasized by Jess, our guide) but noted several large "galls" on the tree. One OED definition of gall is "an excrescence produced on trees, especially the oak, by the action of insects..." They really can be very unsighly, almost like a "tree-goiter." Interesting, but not fatal to the tree.
The Eastern Redbud (Cercis canadensis) was noted not so much for its aesthetic beauty or distinctive look but because it is difficult to establish but then becomes easily managed. In this regard, the Eastern Redbud is like lots of people we know... Here is a picture of its cordate leaves. Speaking of cordate leaves, we also ran into a Little-leaf Linden (Tilia cordata). Here is a picture of its leaves. What is distinctive about the Tilia, however, is its long, yellow, hanging catkin. The OED defines a catkin as a "deciduous spike" or an "amentum." Amentum is the Latin word for thong or strap. Here is a drawing that shows us what we mean.
There was some confusion among us, and even an exemplar didn't clear it up, between the Tilia cordata and the Chinese Tallow (Triadica sebifera or Sapium sebiferum). Here is a picture of the leaves and catkin of such a tree. As you see, the two trees can easily become confused, though as this description tells us, the Tallow in the US is confined almost completely to the South and SE.
There really is much, much more to say, but I will confine my concluding comments to a few special trees. We saw one Canary Island Palm (Phoenix canariensis), a species which gilds the mile-long Palm Drive entrance to Stanford Univ. Jess, our arborist-guide, said that these trees are almost impossible, or greatly undesirable, to prune. The sharpness of the branches on their upper levels makes them actually dangerous to climbers. Perhaps this is why they are also known as "widow-makers." In any case, Jess told us that the smallish pellets atop the tree, when opened, taste just like a coconut. None of us was going to check this out...
We ran into a couple exemplars of the London Plane Tree (Platanus acerifolia; one was a "Yarwood' variety). We learned that these are hardy trees, which you could prune almost indiscriminately and not kill. They are generally susceptible to anthracnose, though the Yarwood variety isn't. Anthracnose, by the way, is defined as "a fungal disease of plants..characterized by dark spots or lesions." Interestingly, the origin of the word is from anthrax, which means "a carbuncle, or malignant boil," and nosos, a disease or illness. Pictures of anthracnose-affected leaves abound. Here is one. Something I didn't know about these trees is that they have pollards at times. A pollard, from the perspective of a dendrologist, is a lopping or cutting back at a branching point. It leads to large "knuckles" being formed, knuckles that can be made into various wood products, including pencils.
Time would fail to tell of so many other things learned there or through study about the things learned there. There were Monterey Pines and Modesto Ashes; Valley Oaks and a Mimosa, even a few Alders. This led to learning about the 33 Native trees to England, which I don't have time to develop here. But that is why there is tomorrow, for most of us, and the opportunity to learn a little bit more than. I hope you have enjoyed the journey.