Bryum chryseum Mitten 1869

Bryum chryseum

Bryum chryseum Mitt., J. Linn. Soc., Bot. 12:304, 1869. [Original material: Volcán de Fuego, Guatemala, coll. Godman & Salvin.]

Small, yellowish green plants to 1 cm high; stems green, very brittle, making stripping of leaves impossible, surface covered with quadrate or short-rectangular cells 15–30 μm long and 20 μm wide; very densely foliate with crowded, spreading leaf tips. Leaves ca. 1 mm long, 0.6 mm wide, with broadly ovate base and long, slender acumination; margins entire, narrowly recurved; costa percurrent to slightly excurrent; basal 1/3 of leaf filled with numerous green, quadrate cells, cells ca. 15 μm wide, 12–15 μm long; upper cells narrowly rhomboidal to linear, 10–12 μm wide, 75–100 μm long. Dioicous. Setae to 20 mm long. Capsule pendulous, cylindrical with a tapering neck; peristome complete.

The species was reported from Juan Fernandez by Bartram (1957) and had previously been known only from Guatemala and Mexico. I have seen many collections from the coastal range of Peru and from western Venezuela. In South America the species may have been confused with Haplodontium, which it superficially resembles.

The green, brittle stems with quadrate epidermal cells are the most distinctive feature of the species.