Bryum

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Bryum (order Bryales) A genus of mosses in which the plants are usually densely tufted. The leaves are ovate or broadly oblong-lanceolate; the cells composing the leaf are uniform and are mainly hexagonal or rhomboid. The capsule is pyriform to sub-cylindrical, horizontal, or pendulous, but never erect; the peristome is double. Bryum is a large cosmopolitan genus, with about 1050 species, some of which are difficult to distinguish. They are mainly terricolous or saxicolous. B. argenteum is easily recognizable on sight: it has a characteristic silvery-green colour, and grows abundantly in many places where little else can grow, e.g. on pavements in towns, roadsides, etc.