Hypnum Imponens MossHypnum imponens, Hedw.
Habit and habitat.-This moss is exceedingly handsome, growing in flat yellowish-green tufts on decayed trunks and about the bases of trees.
Plant )gametophyte).-Prostrate, stems feather-branched.
Leaves.-The stem-leaves overlapping, lying in two rows on the lower side, base broadly ovate, orange, at the angles minutely ear-like ; apex thread-like, and turned to one side ; borders reflexed below, minutely toothed all around or almost entire ; vein double or none ; cells very narrow, linear, somewhat worm-like, enlarged, and 4-sided at the basilar angles, the branch-leaves narrower, hooked, and roiled together at the apex of the branches ; the leaf-like appendages (Paraphyllia) attached to the stem, large, palm-like or lance-like.
Leaves at the base of the pedicel (perichaetial leaves).-Without a vein, gradually narrowed to a long thread-like flexuous and finely toothed point.
Habit of flowering).- Male and female flowers on separate plants (dioicous). Veil (calyptra).-Thin, split up one side.
Spore-case.-Cylindrical, pale-brown, somewhat erect or slightly incurved.
Pedicel (seta).-Long and slender.
Lid (operculum).-Convex, with an oblique point, orange at the apex.
Teeth (peristome).-Inner segments slightly cleft and as long as the cilia; outer, normal, cilia single, with small transverse spurs attached to the margin.
Annulus.-Large, compound, adherent to the mouth.
Spores.-Mature in the autumn.
Distribution. -Common in sub-alpine America, rare in Europe.