''Ptychostomum pseudotriquetrum'', commonly known as marsh bryum, is a species of

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

belonging to the family

Bryaceae Bryaceae is a family of mosses. Genera Genera include:Buck, William R. & Bernard Goffinet. 2000. "Morphology and classification of mosses", pages 71-123 ''in'' A. Jonathan Shaw & Bernard Goffinet (Eds.), ''Bryophyte Biology''. (Cambridge: Cambri ...

. It has

cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in appropriate habitats. Such a taxon, usually a species, is said to exhibit cosmopolitanism or cosmopolitism. The ext ...

. There are two subspecies, Bryum pseudotriquetrum var. pseudotriquetrum and Bryum pseudotriquetrum var. bimum. The moss has an

acrocarpous The Bryopsida constitute the largest class of mosses, containing 95% of all moss species. It consists of approximately 11,500 species, common throughout the whole world. The group is distinguished by having spore capsules with teeth that are '' ...

growth form. The shoots form green to reddish or brown tufts and patches that can grow to be several centimetres tall. The stems are often reddish. The green to yellowish-green leaves are equally spaced along the stem, are 2–5 mm long, have a border of narrow reddish cells, and have a thick nerve that is usually shortly excurrent. Leaves are oblong-lanceolate to ovate-lanceolate. The leaves are contorted when dry and erect-spreading when wet. Most plants have leaves with a base that runs down onto the stem, although this feature is not always well-developed. The lower parts the stems are covered with a brownish red mat of

rhizoids Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be unic ...

. The pendulous or inclined capsules are frequent, 2.5-4 mm long, and borne on a

seta In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. Th ...

2–3 cm long. The capsules are brown when they mature in summer or autumn.

References

pseudotriquetrum {{bryidae-stub