E-Flora BC: Electronic Atlas of the Flora of British Columbia

Species description:
Genus name meaning short sporangium, a feature of many species. Species name meaning very rough, probably in reference to the rough seta.

Reproduction:
Sporophytes common, red-brown, maturing in early spring.

Distinguishing characteristics:
The genus Brachythecium is a very trouble­some one. The shortened, inclined sporangium associated with a creep­ing leafy plant bearing glossy leaves with a single midrib will usually indicate this genus, although related genera can pose difficulties. The rough seta is also a useful feature in this species. This, combined with leaves that are not curved and the epiphytic habitat are usually enough to separate this species.

Habit:
Forming tangled mats of light green, somewhat glossy plants, sometimes with attenuate shoots and branches, especially when growing on branches of trees or shrubs.

Similar Species:
To name this species without sporophytes is hazard­ous, but sporophytes are frequent in spite of the separation of male and female plants. B. curtum usually has a rough seta but the leaves are strongly decurrent (weakly decurrent in B. asperrimum). B. frigidum, a terrestrial species, is extremely similar but is larger and the leaves are sometimes curved. Some workers consider B. frigidum to be identical to B. asperrimum but, besides the usual difference in habitat, B. frigidum often has a twisted leaf apex (not twisted in B. asperrimum) and the alar cells are often enlarged (not enlarged in B. asperrimum). The habit of B. frigidum shows leaves that are closely or slightly spread from the stem while in B. asperrimum leaves are wide-spreading and the shoots some­times appear somewhat flattened.