Phascum ludovicianum Sullivant
Leaves long-lanceolate, base long-elliptic or narrowly ovate, shoulders absent, distal laminal margins plane or erect, apex broadly channeled, acute, mucro very strong, of 7--10(--14) cells; costal adaxial stereid band smaller than the abaxial; distal laminal cells 8--10(--12) µm wide. Sexual condition rhizautoicous. Seta short, 0.08--0.015 cm not including the vaginula. Capsule cleistocarpic, ovoid with a short-rostrate apiculus.
Capsules mature fall--spring. Moist soil, fields, among grasses, roadside banks; Ala., Ark., Fla., Ky., La., Miss., N.C., S.C., Tex., Va., W.Va.
The gametophyte of W. ludovicianum is quite like that of W. brachycarpa. If it has a hybrid origin, then the archegoniate parent is the latter species. Weissia ludoviciana, W. muehlenbergiana, and W. phascopsis are similar in the short-seta, cleistocarpic capsules and long-lanceolate leaves, but differ most constantly in the traits given in the key. Additional differences observed, which may prove inconstant on revision, are: W. ludoviciana is rhizautoicous, with antheridia in extremely small, serrate-leaved buds, on soil near base of the archegoniophore, the capsule has stomates and a weakly differentiated annulus of 3--4 rows of smaller cells, and the calyptra is ca. 1 mm; W. muehlenbergii is cladautoicous, the capsule lacks stomates and an annulus is not distinguishable, and the calyptra is 0.5--0.6 mm; W. phascopsis is cladautoicous, the capsule has stomates and the annulus somewhat differentiated as a ridge, and the calyptra is 1.2--1.4 mm. The hybrid Weissia ludoviciana ´ W. controversa Hedwig was reported by W. D. Reese & B. A. E. Lemmon (1965).