Pottiaceae

Pottiaceae is a diverse family of mosses in the class Bryopsida, order Pottiales. It contains a large group of terrestrial mosses that inhabit a broad range of environments, from deserts and tundra to disturbed soils and rock faces. The family is cosmopolitan, with species described from most continents. The best-known genus is Pottia, and other commonly cited genera include Tortula and Syntrichia.

Morphology and habit: Pottiaceae species are typically small, forming cushions, rosettes, or thin mats on soil, rock, or man-made substrates. Leaves are usually small with a clearly developed costa and often recurved margins; leaf cells are often elongated and may appear papillose under magnification. The sporophyte consists of a slender seta bearing a capsule; in many species the capsule is immersed or partially protrudes, and peristome teeth vary among genera, contributing to diverse spore dispersal strategies. They are frequently desiccation-tolerant and readily revive after brief wet periods.

Ecology and classification: Pottiaceae occupy a wide array of substrates, including soil cracks, moss mats, and disturbed surfaces, and can form important microhabitats in otherwise inhospitable environments. The taxonomy of the family has been refined with molecular data, leading to changes in circumscription and the status of several genera. Overall, Pottiaceae represents a major lineage of mosses with significant ecological breadth and morphological diversity.