Ptychostomum pseudotriquetrum

Ptychstomum pseudotriquem is a medium to large moss with an acrocarpous growth form. It is a yellow-green The stems occur in dense turfs. The stems usually grow to lengths of 2–4cm The stems branch sparingly by means of subfloral innovations, The diplolepidous peristome is composed of two sets of teeth, an inner endostome and an outer exostome, which ring the mouth of the capsule. The exostome teeth are orange- or yellow-brown to pale yellow and papillose at the tips. The yellowish hyaline (i.e. translucent) endostome teeth are lightly papillose, have broad perforations, and have a membrane at the base that is half the height of the exostome teeth. Attached to the endostome cells are 2–3 long, filiform (i.e. threadlike), appendiculate cilia. The operculum (the cap of the capsule) is 0.5–0.8mm long and conic-apiculate, ending in a sharp point. The pale yellow or green spores measure 12–18μm in diameter and are finely papillose. The capsules mature in the summer or fall, in the Northern Hemisphere from April to October. ==Taxonomy==

Bryum pseudotriquetrum is a synonym of Ptychostomum pseudotriquetrum. Ptychostomum bimum has historically been treated as a synoicous form of Ptychostomum pseudotriquetrum. P. bimum has twice as many chromosomes as and probably evolved from P. pseudotriquetrum As of June 2024, World Flora Online treats the two species as separate. Compared to P. pseudotriquetrum, P. bimum has a shorter stem and significantly shorter leaf decurrencies. ==Distribution and habitat==

P. pseudotriquetrum has a bipolar distribution and is additionally found in temperate regions in the Southern Hemisphere. It is found on all continents, including Antarctica, but is largely absent from the tropics, subtropics, and islands in the central Pacific Ocean. It grows on rocks and wet soil by streams and lakes and in fens, wet heaths, and marshes. at elevations of 0–4000m. ==References==