Alvars in the vicinity of Enterprise, Northwest Territories, had 87 species of vascular plants. Of these, 14 were frequent or at least locally abundant, including: Juniperus horizontalis, J. communis var. depressa, Geum triflorum var. triflorum, Carex richardsonii, Populus tremuloides, Elymus trachycaulus subsp. trachycaulus, Koeleria macrantha, Saxifraga tricuspidata, Artemesia campestris subsp. borealis, Senecio lugens, Arctostaphylos uva-ursi, and Galium boreale. Of the trees comprising the surrounding forest, only Populus tremuloides and Pinus banksiana were common in the open areas. The cliff tops had fewer species but they also had some species of arctic and high boreal affinity that were absent from the alvars. Associations characterized by Deschampsia caespitosa occurred in lower areas of alvar that collect run-off, whereas higher areas were characterized by a variety of plants including Carex richardsonii, Elymus trachycaulus, and Geum triflorum. Cracks in the limestone pavement in elevated areas were occupied by Pinus banksiana and Juniperus communis. Approximately 12% of the species present were rare and/or restricted, including Avenula hookeri, Carex filifolia, and Dodecatheon pulchellum. Compared to the alvars of the Great Lakes region, the alvars and cliff tops of Northwest Territories had a much higher percentage of species that were also found in the Beringian region of northwestern North America. Higher numbers of boreal, arctic, and cordilleran species also contributed to the distinctive nature of Northwest Territories alvars, based on clustering of similarity coefficients from species presence or absence data. The alvar flora of Northwest Territories is believed to have been established in the region of Great Slave Lake between 10,000 and 8000 years ago, prior to invasion of the boreal forest. At this time, the northwestern Beringian and Cordilleran floras met the retreating tundra and prairie floras from the south in an expanding ice-free corridor. The relict flora of Northwest Territories alvars and cliff tops includes species of the Beringian steppes and tundras such as Plantago canescens, species of the central North American plains such as Geum triflorum, and many species that could have originated from the prairie-like habitats of either region. This unusual relict flora, originating in early postglacial times, is now isolated within the present boreal forest that spread through the region approximately 8000 years ago.