High macro view of the peristom of a moss spore capsule, fully open showing ripe spores
In mosses, the peristome is a specialized structure in the sporangium that allows for gradual spore discharge, instead of releasing them all at once. Most mosses produce a capsule with a lid (the operculum) which falls off when the spores inside are mature and thus ready to be dispersed. The opening thus revealed is called the stoma (meaning "mouth") and is surrounded by one or two peristomes. Each peristome is a ring of triangular "teeth" formed from the remnants of dead cells with thickened cell walls. There are usually 16 such teeth in a single peristome, separate from each other and able to both fold in to cover the stoma as well as fold back to open the stoma. This articulation of the teeth is termed arthrodontous and is found in the moss subclass Bryopsida. In other groups of mosses, the capsule is either nematodontous with an attached operculum (as in the Polytrichopsida), or else splits open without operculum or teeth.
Size: 3660px × 3315px
Photo credit: © Scenics & Science / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: bryophyte, capsule, damp, forest, fully, high, macro, moss, open, peristom, ripe, showing, spore, spores, view, woods
