Montana Field Guide

Plants: Acrocarpous. Growing in dense (Flowers 1973) to uncrowded clumps of erect shoots, deep green to black with brown tones (FNA 2007), brown below, the surface above somewhat silvery (Flowers 1973). Stems 1-3 cm long (FNA 2007), frequently branched (Lawton 1971); possessing a central strand (FNA 2007).

Leaves: Appressed and overlapping when dry, upright to spreading broadly when wet or the distal leaves spreading about 90 degrees from the stem (Lawton 1971), 1.7-4 mm in length, 0.4-0.8 mm in width, lance-shaped with ovate tendencies, cupped; margins flat, curved inward above (FNA 2007); base enveloping the stem slightly; apex piliferous, the hair-point finely toothed (Lawton 1971), usually with a slender attachment that is not decurrent along the margins (FNA 2007), but occasionally hair-point is stout and decurrent (Flowers 1973), 0.5-1 mm in length; costa slender at the base (FNA 2007), extending to the apex (Lawton 1971); leaves lower on stem becoming shorter and the lowest ones lacking a hair-point (Flowers 1973).

Leaf Cells: Lamina of 2 cell layers, or sometimes thicker in the distal region (Lawton 1971); upper laminal cells square with thick walls; middle laminal cells isodiametric with thick walls; basal laminal cells adjacent to the costa typically long (occasionally short and quadrangular) with walls wavy and thick; basal laminal cells near the margin green, usually transparent, square or elongate, straight, with thick crosswise walls (FNA 2007).

The similar G. longirostris has keeled leaves rather than concave, margins curved back and out rather than flat, and is autoicous rather than dioicous (FNA 2007).

Grimmia laevigata, which also resembles G. ovalis, has a costa that is very wide at the base (to 1/3 of the base width) rather than narrow (FNA 2007).

Dry, partially exposed, noncalcareous rock, such as granite, sandstone, and basalt (FNA 2007, Elliott 2016). Elevation: Usually 3280-8200 feet (FNA 2007).

Dioicous. Fruit produced somewhat infrequently. Perichaetial bracts larger than vegetative leaves. Seta 4-6 mm tall. Capsule carried beyond the perichaetial bracts, ochre; operculum long-beaked; calyptra hood-like (FNA 2007).