Plant macrofossils from the basal inorganic sediments at Tom Swamp, north central Massachusetts, contained leaves, seeds, and fruits of arctic-alpine species, nearly all of which occur at present near the summits of Mt. Washington and Mt. Katahdin (New England) and in other alpine and arctic areas northward in eastern North America. Included were the needle-leaves of the dwarf shrub, Harrimanella hypnoides (L.) Coville, which matched comparative modern leaf samples in all anatomical details. The macrofossil assemblage was deposited before 12,830 \textpm 120 radiocarbon years ago and prior to the expansion of spruce populations in the region. Fossils of H. hypnoides suggest that snow beds were a regular feature of the summer landscape of southern New England during late glacial time. Calculations using the average lapse rate indicate that the mean annual paleotemperature in the Tom Swamp area may have been depressed 8-9 C below present means.