Pellia Epiphylla, A Liverwort

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).

Pellia Epiphylla

Day 250: The things we do for science! A week ago, during a Team Biota field exploration into a new pocket ecology, I discovered a liverwort I had not seen in the Park previously. The area where it occurred was what I describe in my journal as "down in a hole," i.e., in a brushy minor drainage lined with tangled young alder, under fairly well closed canopy (read, "in a dark bit of forest"). I prefer not to use flash when photographing my subjects and, to tell the truth, the option never crossed my mind. Instead, I laid my pack on the wet ground and braced the camera against it. Shooting a long exposure resulted in a less-than-clear image of the tiny sporangia (spore capsules, inset). I did think to take a sample which I examined under the microscope at home to determine that my new liverwort was Pellia epiphylla. That said, I wanted better pictures, so day before yesterday, I returned to the hole alone in the rain. The mosquitoes had hatched in droves, and while I knelt in the wet taking pictures, they attacked through the open space at the back of my brim cap. I got better photos of Pellia, but the few fragile, thread-like setae and sporangia which remained had been beaten down by the rain. It looks like another trip to the hole is on next year's calendar...with bug spray.