Authors: Roxanne I. Hastings & Dr. Henk C. Greven

Plants in loose tufts, green. Stems 0.5--1.5 cm, dichotomously branched, central strand absent. Stem leaves loosely appressed and straight when dry, erecto-patent when moist, broadly oblong-lanceolate, tapering to acute apex, 1.5--2 × 0.4--0.6 mm, larger towards stem tips, sharply keeled, margins recurved on both sides, awns absent, occasionally short hyaline points at leaf tips present, costa weak proximally, broad distally, projecting on dorsal side; distal laminal cells 1-stratose, margins 2-stratose; medial laminal cells short-rectangular with nodulose to sinuose walls, weakly papillose; basal juxtacostal laminal cells rectangular to linear, straight, thin-walled; basal marginal laminal cells rectangular, straight, thin-walled. Gemmae absent. Sexual condition dioicous. Seta straight, 2 mm. Capsule occasionally present, exserted, yellowish brown, obloid, smooth, exothecial cells thin-walled, annulus present, operculum rostrate, peristome teeth orange, deeply split and perforated, papillose. Calyptra cucullate.

Damp acidic rock; of conservation concern; 2000--3000 m; Calif., Wash.

Grimmia lesherae is apparently endemic to the high mountains along the Pacific Coast of western North America. At present, it is known only from a few damp high elevation sites in Washington and northern California, but suitable habitats exist all along the high coastal mountains and so it may also be expected in Oregon. Grimmia lesherae is a characteristic species that is unlikely to be confused with other Grimmias. There are some similarities to G. incurva, but that species has short hair-points, the leaves are linear, the medial cells have nodulose walls, and the seta is arcuate. The combination of keeled leaves with recurved margins, and straight seta is unknown in subg. Rhabdogrimmia, and questions the division of the genus into three sections because these plants are clearly intermediate between the subg. Guembelia and Rhabdogrimmia. A peculiar distinguishing character is the left-handed twist of dried up setae, unique to this species in Grimmia. G. K. Limpricht (1890) incorrectly reported the left-hand twisted dried up setae as common in Grimmia.