alpine grimmia

Grimmia sessitana is a moss with a dense, compact growth form, adherent to the substrate via rhizoids. The gametophyte is mostly monoicous, though occasionally dioicous. Female plants have innermost perichaetial leaves that are sheathing, 2.6–2.8 mm long, and concave. Male perigonia appear as buds on short stalks on the branches of female plants, either terminal or in leaf axils. The leaves are crowded at the base of the stem, gradually increasing in length to 2.4 mm. They are lanceolate, with a nearly smooth hair-point and a keeled lamina. The leaf margins are recurved on one side or plane on both sides. Basal paracostal cells are elongate-rectangular with thin walls, and marginal cells are hyaline and gradually disappear at the broadest part of the leaf.