Crossidium Moss

Crossidium squamiferum is a distinctive species characterized by a whitish marginal area on the distal half of the leaves, thick-walled distal leaf cells, a long hyaline hair point, thick-walled filaments ending in a papillose terminal cell, and the gonioautoicous sexual condition. North American specimens without sporophytes from Arizona, California, Colorado, and Utah have been studied, but these cannot be satisfactorily referred to an infraspecific category. The type specimen of C. succulentum is also sterile.

Plants 6-10 mm. Leaves deltoid-ovate, oblong-ovate or lanceolate, 0.6-2 mm, margins recurved to erect distally, usually undiffer-entiated, apex obtuse or rounded, serrulate, with abaxial papillae, piliferous; costa excurrent, with an inconspicuous abaxial epidermis, filaments of 4-10 cells, cells cylindric to subspheric, [thick-walled, terminal cell rectangular, subspheric or conic with 2-5 solid papillae; cells of leaf base 11-70 µm, medial and distal cells 9-33 µm, smooth, thick-walled. Sexual condition gonioautoicous. Seta 5-20 mm. Capsule urn short-cylindric to ovoid-cylindric, 1-2.7 mm; operculum 0.6-1.1 mm; peristome short, nearly straight, cribose at base to long and strongly twisted, 198-1160 µm. Spores spheric, 9-22 µm.

Plants very small, 3–5 mm high, yellowish green with whitish sheen, because of hyaline excurrent costae, in low gregarious or thin tufts. Stems very short, erect, mostly buried in soil, simple; central strand present. Leaves imbricately appressed when dry, slightly spreading when moist, broadly ovate to rounded ovate, concave, abruptly to broadly acute at the apex; costa slender, shortly excurrent as an apiculus or excurrent in a short, smooth, hyaline awn; superficial cells of upper ventral costa forming a group of separate, often branching, filaments; in cross section a dorsal stereid band present; margins entire, slightly recurved above; upper leaf cells subquadrate to rounded elliptic, thick-walled, without papillae; basal cells rectangular, thin-walled. Dioicous. Outer perichaetial leaves similar to stem leaves, inner perichaetial leaves smaller. Setae elongate, slender, more or less straight, reddish brown, 6–7 mm long; capsules oblong-ovoid, erect or curved; annuli differentiated, of 3 rows of cells, persistent or deciduous; peristome teeth 16, divided into 32 linear-lanceolate segments, papillose, twisted counterclockwise, rarely straight; opercula conic, obliquely short-rostrate. Calyptrae cucullate, smooth. Spores small, spherical, yellowish brown, smooth.

Distribution: China, Mongolia, Russia, Europe, North America, Africa, and New Zealand.

Habitat: on soil or limestone.

Barbula squamifera Viviani, Ann. Bot. (Genoa) 1(2): 191. 1804; Tortula squamifera (Viviani) De Notaris

Crossidium chloronotos (Brid.) Limpr., Laubm. Deutschl. 1: 645. 1888. Tortula chloronotos Brid., Muscol. Recent. Suppl. 1: 253. 1806.