Polytrichum appalachianum Anderson, sp. nov., is described as a new species. Limited to the southern Blue Ridge Province of the Appalachian Mountains, it has previously been known as P. xanthopilum Wils. [Polytrichastrum xanthopilum (Wils.) G. L. Sm.]. Recently discovered sporophytes from North Carolina, however, show clearly that American plants do not belong to this species, necessitating the description of a new taxon. The new species differs from P. xanthopilum principally in its lack ofa bulbous hypophysis at the base of the capsule, the absence ofa constriction between the urn and hypophysis, and a less pyriform terminal cell of the leaf lamellae. The new species resembles most closely P. formosum Hedw. and P. longisetum Brid. Its distribution, ecology, and cytology are discussed. In connection with his generic studies of the Polytrichaceae, G. L. Smith (1971) discovered a previously unrecognized species ofPolytrichum in North America that was narrowly restricted to the higher elevations of the southern Blue Ridge Province of the Southern Appalachian Mountains, specifically in North Carolina and Tennessee. All the specimens that Smith examined are sterile and originally had been identified as P. longisetum Brid. (P. gracile Turn.), P. pallidisetum Funck, or P. commune Hedw. Based on similarities in the structure of the terminal cells of the leaf lamellae, Smith identified this sterile material as P. xanthopilum Wils. ex Mitt. [as Polytrichastrum xanthopilum (Wils. ex Mitt.) G. L. Sm.], a Himalayan species. Crum and Anderson (198 1) included the species in their flora of eastern North America (as Polytrichum), but with some reservations: We have no reason to disagree with his [Smith's] opinion, although the Appalachian plants are not a perfect match for plants we have seen from Nepal (collected by Z. Iwatsuki) .... In American plants the lamellae are somewhat shorter, and the terminal cells are not particularly bottle-shaped. Recently, I discovered fruiting plants of this taxon in North Carolina and the capsules differ significantly from plants of P. xanthopilum from Nepal. The American plants clearly do not belong to this species and I have been unable to locate any other species with which the Appalachian material can be associated. It is necessary, therefore, to describe a new species. Polytrichum appalachianum, sp. nov. (Fig. 1-7) P. xanthopilum auct. amer., non Wils. ex Mitt. Polytrichastrum xanthopilum auct. amer. Cellulae terminales lamellarum in sectione transversali oliquanto pyriformes, parietibus apice incrassatis, e latere irregulariter et obtuse serrulatis. Capsula quadrangularis, operculo rostrato, apophyse inferne evoluta. Plant 2-10 cm high, dark green to blackish, in loose, often semi-erect tufts, shorter plants more densely aggregated and erect. Stems simple, rarely forked, sparsely to densely radiculose, often with whitish tomentum extending well up the stem. Leaves erect-spreading when dry, often recurved at the tips, more crowded in short, erect plants, when wet widely spreading and generally somewhat recurved, 5-10 mm long, lanceolate-acuminate from a sheathing base about 2 mm long, ending in a short to moderately long, dark to red-brown toothed point; margins sharply serrate nearly to the base of the 0007-2745/87/1-5$0.65/0 This content downloaded from 157.55.39.58 on Sun, 31 Jul 2016 05:27:34 UTC All use subject to http://about.jstor.org/terms 2 THE BRYOLOGIST [Volume 90