Bryum knowltonii Barnes, known previously in North America only from northern Canadian stations, has been found in arctic-like tundra of the Mount Zirkel Wilderness in Colorado. Bryum knowltonii Barnes was collected August 1981 in the Mount Zirkel Wilderness, north-central Colorado. The habitat is flat to gently undulating tundra, usually wet, arcticlike rather than the typically drier alpine tundra in Colorado. This species is known in North America from Funk Island, Newfoundland, from Southampton Island, Northwest Territories, and from Fort Churchill, Manitoba. Andrews (in Grout 1936) reported it from a few localities in arctic America, south to Newfoundland. Determination was made by Elva Lawton and confirmed by A. C. Crundwell, with the assistance of F. J. Hermann. Diagnostic features include indistinctly bordered ovate leaves, revolute to the apex or nearly so, acute to shortly acuminate, with costa subpercurrent to slightly excurrent, synoicous reproduction, capsules broadly pyriform, pendent, with a short, distinct neck, and spores 16-27 um. Endostome segments are narrow and the cilia rudimentary. A helpful characteristic, pointed out by Dr. Crundwell, is that the capsules mature at different times instead of simultaneously as in most Brya. Crum and Anderson (1981) give a complete description. Grout's Moss Flora and Bryologia Europaea use the synonym B. lacustre. United States collection: COLORADO. JACKSON CO.: Rainbow Lakes Trail approaching the Continental Divide, just W of the Roxy Ann Lake turnoff, 1 km N of Mt. Ethel, 3400 m, 40?40'00N, 106'40'35W, Rolston 81106 (coLo; GL; NY; US; WTU). Bruch, P., W. P. Schimper & T. Giimbel. 1836-1855. Bryologia Europaea. 3 Vols. Reprint (1971). A. Asher, Amsterdam. Crum, Howard A. & Lewis E. Anderson. 1981. Mosses of Eastern North America. 2 Vols. Columbia University Press, New York. Grout, A. J. 1936. Moss Flora of North America North of Mexico. Bryaceae. Newfane, Vermont. 2: 219-220. 007-2745/82/420$0.25/0 This content downloaded from 157.55.39.45 on Fri, 02 Sep 2016 06:13:29 UTC All use subject to http://about.jstor.org/terms