Two vascular plants, 18 lichens, and five bryophytes were collected above 2,140 meters (7,000 feet) on an exposed ridge of an alpine summit on the north side of the Alaska Range. The vascular plants, Chrysosplenium wrightii and Saxifraga oppositifolia, were found up to 2,195 meters (7,000 feet) and 2,165 meters (7100 feet) respectively. Several of the mosses were found as high as 2,286 meters (7,500 feet), and several lichens grew above 2,320 meters (7,600 feet). Plant collections from high altitudes in the Alaska Range are rare. In most locations, perpetual snow limits the upper distribution of plants to between 1,830 meters (6,000 feet) and 2,140 meters (7,000 feet). Briggs (1953) and Webster (1961) both report the upper limit of vascular plants in the Alaska Range to be 2,140 meters (7,000 feet). Lichens and mosses were found much higher in isolated areas of exposed rock and rubble where snow does not accumulate. This is in contrast to the high Himalayas where Swan (1961) reports that lichens are scarce above 5,486 meters (18,000 feet) but that vascular plants go as high as 6,100 meters (20,000 feet). On August 6, 1962, I had an opportunity to collect plants on a summit at 2,354 meters (7,723 feet) on the north side of the Alaska Range in the vicinity of Dry Creek, about 120 kilometers (70 miles) south of Fairbanks. The summit, at 63050'N and 147004'W, is the highest elevation in a three-way divide between Dry Creek, the Wood River, and the West Fork Little Delta River. The bedrock of the peak consists of granodiorite, most of which has been fractured into large boulders and smaller particles down to coarse sand. This rock type contrasted conspicuously with the sedimentary rocks of the surrounding lower mountains. The north-facing slope of the mountain from 1,830 meters (6,000 feet) to the summit was mostly covered with permanent ice and snow fields. The south side formed a steep, snow-free cliff from 1,980 meters (6,500 feet) to the summit and appeared to be too steep and actively eroding to present habitats for plant growth. Viewed from the north, the rocks were conspicuously darkened by a cover of Umbilicaria. A treeline of white spruce (Picea glauca) and black spruce (Picea mariana) occurs in the area at approximately 1,100 meters (3,600 feet). Above this is a zone of bog birch (Betula glandulosa) and willows (primarily Salix alaxensis, S. richardsonii, and S. pulchra). Above the shrubs and extending down through them on exposed ridges is a zone of low matted alpine vegetation. The alpine zone consists of a mosaic of several vegetation types, the most common being a Dryas octopetala mat form. The distribution of the alpine vegetation type is largely controlled by snow depth, elevation, slope, wind exposure, and substrate. Above 1,830 meters (6,000 feet), the vegetation cover becomes sparse and consists, in addition to mosses and lichens, of small clumps 1 Field work for this study was done while I was employed by the Alaska Department of Fish and Game. 2 Institute of Northern Forestry, Pacific Northwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture, Juneau, Alaska. This content downloaded from 157.55.39.235 on Fri, 07 Oct 2016 06:09:08 UTC All use subject to http://about.jstor.org/terms 346 THE BRYOLOGIST [Volume 70 and isolated individuals of such species as Dryas octopetala, Luzula nivalis, Silene acaulis, Saxifraga oppositifolia, Salix phelbophylla, and Draba spp. The location of the following collections was on a narrow southeast-facing ridge extending from 2,140 meters (7,000 feet) to the summit of the mountain. (The elevations were determined with a pocket altimeter.) The ridge consists of large blocky boulders of granodiorite between which are weathered, loose, small particles of the same material. The bare rock and sand surface is about ten feet wide, giving way on the northeast to a steep ice cliff and on the southwest to a steep rock cliff. The lichens have been determined or verified by Dr. John W. Thomson and the mosses by Dr. Herman Persson. The collection numbers are mine. Specimens are in the herbarium of the University of Alaska.