Day 205: Every spring, at least one plant's identity will elude me as I'm walking through the forest, refreshing my memory as I go by addressing each species with its Latin binomial or, failing that, its common name. Some I've drilled so thoroughly into my brain that they no longer require deep digging with the Alphabet Tool ("A, B, C...c...ca, ce, ci, co, cu...ca...car...has something to do with heart...cardio...Cardamine!"), but others frustrate my best efforts to mine out the sequence of letters which will give me the necessary clue. Such was the case when I found a patch of liverwort on the Reservoir Trail in Pack Forest a few days ago. I could get no farther than "not Marchantia," and that only because the morphology of the specimen told me it was something else. In any event, it covered roughly three square feet of mud and rock in the most damp and dismal section of the trail, perfect habitat if you're a liverwort, and at least that much was obvious. Eventually, I was distracted from the alphabet by trying to keep upright in an exceptionally muddy stretch and then forgot about it until I got home.
Liverworts are less common than mosses, and although they share a number of features with them (reproduction by sporulation, for example), there are others which set them apart. Most contain oil bodies in the cells of their leaves, and mosses do not have this characteristic. In many species, these oil bodies can be seen with the naked eye or minor magnification. Liverworts may be either leafy or thalloid (as above); mosses are always leafy. Another less definitive difference is that there are numerous field guides available for mosses, and darn few for liverworts, and thus their identification becomes more difficult. Consider yourself fortunate if you can place a liverwort in its proper genus. For anything further, you may need professional help as I did when I first encountered this species (Pellia epiphylla).
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