Genus name from the hairless calyptra, compared to the hairy calyptra of Polytrichum. Species named in honour.of A. R. C. Selwyn, director of the Geological Survey of Canada from 1869 to 1895.
Sporophytes common and abundant; seta and sporangium reddish-brown, maturing in late winter to early spring.
The extremely low lamellae on the midrib, the teeth in diagonal lines on the lower leaf surface, the markedly contorted leaves when dry, combined with the smooth calyptra distinguish this genus from others related to it.
Forming loose turfs of light to dark green plants with sporophyte-bearing plants in colonies usually somewhat separate from male plants.
From A. undulatum it is most readily distinguished by the sharper marginal teeth and more sharply acute apices compared to the blunter points of A. selwynii. From A. tenellum it differs in narrower leaves that are more acute than in A. selwynii; the sporangium is usually also shorter in A. tenet/um. A. selwynii is the common species in non-urban sites near the coast while A. undulatum is a frequent urban "weed" of gardens and road margins. Oligotrichum parallelum of subalpine sites has less acute teeth on the leaf margins and sporophytes are usually light green, rather than dark brown, when mature. Comments: This genus is sometimes transplanted to Japanese tea gardens as an attractive ground cover.
If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.
Illustration Source: Some Common Mosses of BC
Synonyms and Alternate Names:
Atrichum rosulatum C. Mnll. & Kindb. in Mac. & Kindb.
Atrichum undulatum var. selwynii (Aust.) Frye in Grout