R. Brown

Trans. Linn. Soc. London 12: 561. 1819 ,.

Etymology: For Sir Charles Lyell, 1767–1849
Treatment appears in FNA Volume 27. Treatment on page 159. Mentioned on page 122, 123, 124, 161.

Plants robust, polytrichoid. Stems simple or rarely branched. Leaves with a sheathing base and divergent blade; sheath entire, hyaline-margined; limb firm, serrate-toothed in distal 1/3–1/2, with lamellae restricted to median portion of the limb, the lamina ± uniformly 2-stratose; lamellae entire, the marginal cells in section not differentiated, smooth. [Capsule ovoid, strongly dorsiventral, the upper surface flattened and concave with a narrow winged margin, lower surface rounded-convex, with hypophysis short, with conspicious stomata, guard cells surrounded by a circle of thin-walled, hyaline cells; operculum compressed-conic, with elongated oblique beak; peristome none; columella apex flattened and protruding from the central opening of a concave, thickened disc. Calyptra sparsely hairy to almost smooth. Spores echinulate.]


North America, e Asia (including Siberia).


Species 4 (1 in the flora).

Lyellia is a small genus with a disjunctive distribution, with representatives occurring in the Himalayas and eastward, and a single species, L. aspera, at high latitudes in arctic America and eastern Asia. The capsules are strongly dorsiventral, resembling those of Dawsonia in shape, but without a peristome. The flattened columella apex projects from the center of the disc like a stopper in a wash basin (Gary L. Smith 1971, fig. 25); the epiphragm remains embedded in the operculum. The hypophysis has prominent stomata, the guard cells surrounded by a ring of thin-walled, hyaline subsidiary cells, which are sharply differentiated from the surrounding cells of the exothecium.

Selected References


Lower Taxa