Day 28: I've often said that if you hold still more than five minutes in the Pacific Northwest, you're likely to be colonized by lichens or moss. The trees in my yard host a variety of species and I'll admit it: I haven't identified them all. The Usneas are particularly difficult, so I set myself a microscope exercise for the morning and after close study of this specimen from the pussywillow's branches, determined that it is U. filipendula. This uncommon species is characterized by round branches which are not cigar-shaped, bearing tall papillae (small bumps) and tuberculate soralia (raised openings in the cortex). Annular cracks are inconspicuous, although the microscope reveals them near the bases of the fibrils. Had you observed this lichen a month ago, you would have found that it was stiff and dry. Rain and cool temperatures have returned it to a soft and pliable state. Lichens are remarkable in their ability to survive with very little available moisture, and like this Usnea, they hold onto whatever they can get.
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