Taxon	Illustrator ⠉
	Meiotrichum lyallii	Patricia M. Eckel

Plants robust, polytrichoid. Stems simple to freely branched. Leaves with a sheathing base and divergent blade; sheath entire, hyaline-margined; limb firm, serrate-toothed to the sheath, broadly lamellate on the adaxial surface; lamellae entire in profile, the marginal cells with the free wall thickened, the cuticle longitudinally striate and pitted. Capsule ventricose, 4–6-angled; hypophysis rugose, with conspicuous stomata; exothecial cells with rounded to slitlike thin spots in the external wall; operculum hemispherical, with a stout, hooked beak; peristome present, leiodont, teeth 64, simple. Calyptra sparsely hairy. Spores papillose.

Distribution

w North America

Discussion

Species 1.

Meiotrichum was originally placed in Polytrichadelphus (Müller Hal.) Mitten (not present in our area) because of the fastigiate habit and sparsely hairy calyptra. All Polytrichadelphus species have lamellae which are crenulate in profile, the marginal cells smooth and flask-shaped in section, a dorsiventral capsule with two sharp angles, and multiple stomata dispersed over the exothecium, none of which occurs in Meiotrichum.

Selected References

None.

Lower Taxa

Meiotrichum lyallii

"broadened" is not a number.