genera of the polytrichaceae in texas

There are three (3) genera in the Polytrichaceae family found in Texas: Atrichum, Polytrichum, and Pogonatum. By far the most common species is Atrichum angustatum (Bridel) Bruch & Schimperer, followed closely by Pogonatum brachyphyllum (Michaux) P. Beauvois, then finally Polytrichum commune Hedwig var. commune. Other species occurring in the state are Atrichum cylindricum (F. Weber) G.L. Smith and Pogonatum pensilvanicum (Hedwig) P. Beauvois (however these two species are much less frequently collected). One of the more characteristic morphologies of this family is the presence of adaxial lamellae on the leaves (although lamellae are not restricted to the Polytrichaceae family). Additional differences between genera are noticeable in the leaf shape and size, as well as plant stature.

POGONATUM - P. brachyphyllum is an early successional species typically occurring on bare soil along road cuts, stream banks, and rocky outcrops. Plants (gametophytes) are scattered on a verdent green persistent protonema and consist of a few (5-7) closely clustered leaves. Leaves are short (1.5-3.0 mm) with an acute to somewhat obtuse apex. The lamellae in this genus are distributed across the entire width of the leaf and therefore completely obscure the broad underlying costa. Sporophytes are frequent, and are long exserted above the basal leaves.

POLYTRICHUM - Polytrichum commune var. commune is one of the larger mosses in Texas, in terms of vertical height, with plants (gametophytes) reaching 10 cm in height. From a superficial perspective the plants resemble miniature pine seedlings. The leaves are narrowly lanceolate with a sharp apex and range from 6-8 mm in length. As in Pogonatum above, the lamellae are distributed across the entire width of the leaf obscuring the broad costa beneath. Sporophytes are rare in Texas, but when present, the seta is long exserted beyond the upper stem leaves.

ATRICHUM - Atrichum angustatum is a fairly common species in many parts of central and east Texas. Often found in shaded to partly shaded woodlands and forests, it is common along creek-banks and roadside embankments. Plants (gametophytes) are variable in height ranging from 1-3 cm and grow in closely aggregated colonies on soil. Leaves are 4-8 mm, narrowly ligulate to oblong-lanceolate above and strongly transversely undulate, with prominent teeth in oblique rows on abaxial surface corresponding to the undulations. Lamellae are much fewer than in Pogonatum and Polytrichum and are located above the much narrower, circular to somewhat elliptical costa. Sporophytes are frequent and well exserted above the plants.