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Thoughts on dichotomous keys

I like plants. I'm a plant guy. So when I go for walks or hikes, I look for interesting plants. Recently I went on a hike and saw such a plant. Buckwheat. It caught my attention because it looked like the same species I have in my own yard. Neat. I snapped a picture and moved on.

Now, the discerning among you would say "But Mike, there are over 250 wild buckwheat species, which one are you talking about?" Well, my friend, according to my plant list, the one I have in my yard is Eriogonum grande var. rubescens, Red-flowered Buckwheat, and I was pretty sure the one I saw was the same. But when I got home I looked it up. Apparently it pretty much only grows on the Channel Islands, and that wasn't where I was hiking. And it also made me wonder why I have it in my yard. When you go for a California Native yard, how close to home should "native" be? 🤔

I went on a quest to figure out what I saw. I headed to iNaturalist and filtered by Eriogonum in the area I was hiking. I pretty quickly found observations of Eriogonum nudum, Nude Buckwheat on the trail I was hiking. Apparently that sucker grows all over the place. And it looks really similar to Red-Flowered Buckwheat, at least when its flowers are red.

Now I wanted to know what the difference was. So I consulted the trusty dichotomous key of California higher plants: The Jepson Manual.

Here is the split between the two species.

The first option leads to grande...

Involucres 3–6 mm wide; stem, inflorescence glabrous (to sparsely tomentose); inflorescence ± head- to cyme-like; leaf blades densely tomentose abaxially, tomentose to ± glabrous adaxially; ChI

The second option to nudum...

Involucres (1.5)2–4 mm wide; stem, inflorescence glabrous to tomentose; inflorescence head- to umbel- or cyme-like; leaf blades tomentose to densely so on both surfaces, or tomentose to glabrous adaxially; mainland

So which description most closely matches the plant I saw? Consult the photograph...

Eriogonum nudum

... and realize that taking a blurry picture of part of an inflorescence isn't going to cut it.

Back in college when I was taking plant identification classes, the professors would scold students who took pictures without taking notes and sketches. And here I am, twenty years later. A fool. Anyways, all this is to say that you should take the time to observe nature. Put the camera down and take notes.