Lyell's Orthotrichum Moss

Orthotrichum lyellii Hook, & Tayl
Muse. Brit. 76. 1818.
Plants robust, 2-6 cm. high, brownish-green to olive-green above, brown below, in rather loose, soft tufts; stems erect to ascending, branched; leaves of European plants bearing numerous brown, septate brood-bodies, mostly rather rigid and closely imbricate, varying to loosely imbricate and almost crisped in a few instances, when moist widely spreading, narrowly longlanceolate from an oblong base, more or less undulate near the apex, acute, 3-4 mm. long, the margins usually plane and somewhat irregular in outline above and often finely and sharply denticulate with large papillae, usually plane at the base and somewhat revolute for a varying distance in the widest part; leaf-cells typically papillose with large, salient, conical to linear papillae except near the insertion, the basal oblong-linear, smooth, usually incrassate, sometimes as thick-walled as the upper, gradually changing into the rounded or elliptic, strongly incrassate upper cells, 10-12 p. in diameter; papillae, at least in the lower portion of the leaf, occasionally bifid; dioicous; seta about 0.5 mm. long; capsules immersed to emergent, oblongovoid, the neck often as long as the urn proper, which is 1-2 mm. long, with 8 well marked ribs when dry; calyptra large, oblong-conic, hairy; exothecial cells well differentiated along the ribs;
stomata superficial, very few, near the base of the spore-sac ; annulus present ; operculum conicrostellate; peristome double, the teeth 16, slender, densely and finely papillose, revolute when dry, the segments large, of 2 rather irregular rows of cells, papillose, nearly as long as the teeth, easily broken; spores 25-35 /* in diameter, maturing from winter to early spring.
Type locality: Europe.
Distribution: On trees; California; Europe; Asia; Africa.