Long-leaved Thread Moss

Ptychstomum pseudotriquem is a medium to large moss with an acrocarpous growth form. It is a yellow-green moss that becomes red-brown with age. The stems occur in dense turfs. The stems usually grow to lengths of 2–4 cm but can be as short as 1 cm and long as 6 cm. The stems may be weakly comose (i.e. crowned with a tuft of soft leaves) or evenly foliate. The lower part of the stem is matted with papillose red-brown rhizoids. The stems branch sparingly by means of subfloral innovations, which are elongate and evenly foliate. The leaves typically measure 2–3 mm in length, but may as short as 1 mm or as long as 4 mm. The leaves are glossy and green, red-green, or yellow-green when young. They become dull brown-red or brick-red with age. They are twisted and contorted when dry. When moist, they are erect spreading, oblong‑lanceolate to ovate‑lanceolate, and flat to weakly concave. This means that the leaves are widest near the base and taper to a point. The leaves' cell walls are firm to incrassate and sometimes porose. The reddish basal cells are rectangular. The distal cells are rhomboidal-hexagonal to hexagonal, with a length of 20–40 μm and a width of 12–20 μm. The leaves are bordered by 2–3 rows of narrow, thick-walled, usually red cells. The leaf margins are revolute (i.e. rolled downward) from the base of the blade to the middle of the leaf or further. …

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 0–4000 m.

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