Some Arctic-Alpine Mosses from the Central Rocky Mountains

Abstract

During the summer of 193I, Miss Ruth Ashton, of the Rocky Mountain National Park in northern Colorado, made a collection of all the mosses she found above timberline on Flattop Mountain and sent them to the author for determination. Since the collection is believed to be fairly complete and also representative of the moss flora in the Arctic-Alpine zone of the higher mountains, the following notes may be of interest. Flattop Mountain is on the continental divide, and is located near the center of the park in what is known as the Front Range. Timberline is about I I,OOO ft., and the highest point on the mountain is about 12,000 ft. Between these elevations the region is strewn with boulders of all sizes with patches of rocky and sandy soil between them, and it was in this region that the mosses were collected. The following is a list of the species found: Ceratodon purpureus Brid. In rock crevices and sandy soil: occasional. Grimmia trichophylla Grev. var. Muehlenbeckii Husn. This was the only Grimmia found. It forms small patches on the larger boulders. Not common. Hypnum revolutum (Nutt.) Lindb. One of the commonest mosses in the mountains at lower elevations, but not very common above timberline. Forming large, thin mats on rocks in shady places. Orthotrichum laevigatum Zett. In small, dark patches on large rocks in shady places. Collected but once. This seems to be the commonest Orthotrichum at higher elevations, replacing 0. cupulatum Hoffm. which is the usual species from 6,ooo to 9,000 ft. Pogonatum capillare (Mx.) Brid. Forming extensive mats on sandy and gravelly soil in moist places. One of the commonest mosses collected, and limited to the higher elevations entirely. In fine fruit in midsummer. Polytrichum piliferum Schreb. The commonest species collected. Forming large mats on sandy and rocky soil in moist places, but apparently never fruiting at higher elevations. Schwartzia montana (Lam.) Lindb. In rock crevices in moist, shady places. Not very common at this altitude, but very common below timberline. The author wishes to express his gratitude to Prof. G. N. Jones of the State College of Washington for aid in determination of the Grimmia. DEPARTMENT OF BOTANY, UNIVERSITY OF WYOMING