The Importance of Comparison and Fieldwork, Tree Version

When you start looking at things and trying to know things, it is important to get some experience in looking at things IN PERSON and IN REAL LIFE. The computer is helpful, field guides are helpful, all of that is wonderful but even more wonderful and super and great is going out INTO THE WORLD and looking at things, hopefully a lot of things.

Let me illustrate. Let's say that you have three species of tree that are native to your area... let's say they're (a) Prunus serotina (black cherry) and (b) Betula lenta (black birch) and (c) Fagus grandifolia (American beech). Here is a picture of them, side by side for easy comparison.

You know from your tree guides that each of these trees has an alternate leaf structure and fairly slender, graceful twigs. If it were summer, you could compare leaves, but it's winter and you still want to look at trees. This is where some time in the real world (or a dendrology textbook that is priced beyond the realm of mere mortals) will help you.

With some time in the real world, you get to know your trees a bit better. You might learn that Prunus serotina smells horrible if you bruise the bark on a twig or break one off. Seriously, it's a bitter, poison smell. (A fairly small quantity of wilted black cherry leaves can kill horses. I think it has something to do with cyanide-ish chemicals in the leaves.) Good to know and also diagnostic.

You might notice that Betula lenta smells (and tastes) like wintergreen. It's a very nice, strong wintergreen-y smell and it is not subtle or easy to confuse with other things.

For its part, Fagus grandifolia doesn't smell like much of anything but if you spend some time in the woods in winter, you soon learn that its slender, graceful twigs tend to retain their leaves. For this reason, you can spot an American beech pretty far off in the woods during winter, once you know to look for the light brown, pale leaves clinging to it.

(There are a lot of bark pictures posted here on iNaturalist and that's all right as far as it goes, but bark is hard to judge without scale and many trees exhibit different bark forms at different parts of their lives. If you want to go by bark, I'm not exactly your huckleberry over here. Bark should only be one part of your winter diagnostic tool set, not the whole of it.)

But even more than helpful and fun facts about what trees smell like (and if you think that's not diagnostic, you've never smelled black cherry, sassafras, tulip poplar, black walnut, hickory... seriously, smell is a helpful diagnostic sometimes.), getting to know your trees in person means that you can differentiate these three twigs (above) even when they're one-by-each and not stacked together so that you can see how different they are despite being all 'slender branches with alternately-arranged leaves".

Practice and experience will help you learn that Prunus serotina has tiny, roundish buds and a very straight twig structure that doesn't zig-zag at all.

Practice and experience will teach you that Betula lenta zig-zags a little bit and has slender, pointy buds that diverge from the stem a bit.

Practice and experience get you to where you find the extremely long and very pointy, strongly divergent buds of Fagus grandifolia diagnostic even if you didn't notice the retained foliage when you gathered the twig to study.

Real world experience helps you base your identifications on more than just one quality. You don't identify using just one thing (most of the time) -- you use several things. I don't know it's black cherry because it smells bad. I know it's black cherry because it smells bad AND the buds are right AND the bark is right AND (let's be honest, here) it's growing alongside my yard and I remember the dangling white flowers from last summer. It's a black cherry I know personally, OK? (It was like 37 F and snowing out when I gathered these twigs for you. I wasn't going to go hunt up a different cherry when I had one mere steps from the door.) But even if it wasn't the one in my yard, I would still know it for a black cherry because of a variety of markers.

I don't know it's a black birch because of the wintergreen. I know because of the main trunk bark and the wintergreen and the graceful twigs that are planar on the branch (very flat) and the brown bark on the twigs and the pointy-ness of the buds. There are many things that go towards "black birch" and not just one thing.

It's an American beech because of the smooth grey bark, the almost formal pyramid shape of the tree, the retained blonde-brown winter foliage, the extremely long, very divergent, super-pointy buds. All of those things go for American beech, not just one.

My point here, iterated three times because it is important, is that identification of these species should be a gestalt for you... not just ONE point of comparison (slender, alternately-arranged leaves) but MANY points of comparison. Field guides do the best that they can, but most consumer ones are not going to include all the things that you will notice (and remember) for yourself out in the field. Real world experience at identifying actual trees, will make you a better identifier, a more confident identifier, an identifier for all seasons.

So, get out there and look at some trees!

(For those of us in the mountains of the Northeastern US... Quick, before the leaves get here!)

Publicado el marzo 6, 2018 11:43 TARDE por whichchick