|A showy array of Polytrichum
piliferum, one of our commonest Haircap mosses. Studded among its hoary white, hair-tipped leaves, which give it a soft gray-haired look, are the red, jewel-like "flowers" (perigoneum) of the male plants. And rising splendidly into the air are the beige "hair caps," like scalps dangling from spear tips. These are the hairy-like calyptra of the sporophytes on the female plants that give it the name
Polytrichum, "many hairs." P. piliferum prefers an exposed, often hot and dry location, and may be found in the thin soil slowly inching out over the diminishing surface of a flat boulder. In hot dry weather, the
polytricha, which absorb and give off moisture only from the upper side of the leaf, flatten their leaves upward against the stem, thus sealing their moisture in.