RECENT DISCOVERIES OF SOUTHERN VASCULAR PLANTS AT THEIR NORTHERN LIMITS IN THE GRANITE BARRENS AREA OF LENNOX AND ADDINGTON COUNTY, ONTARIO

Aristida dichotoma (Poverty-grass), Eleocharis engelmannii (Englemann' s Spike-rush), Lindernia dubia var. anagallidea (False Pimpernel), Que rcus ilicifolia (Bear Oak), and Rotala ramosior (Branched Toothcup) ar e disjunct in the granite barrens of Lennox and Addington County. Quer cus ilicifolia occurs in dry, open scrub communities developed on shal low soil over granite rock, and is an addition to the native shrub flo ra of Canada. The other taxa were found within the annual fluctuation zone of open, biotite-rich metasedimentary rock shorelines, and were p reviously known from the Carolinian zone of extreme southwestern Ontar io. The nearest populations of Quercus ilicifolia and Aristida dichoto ma are about 230 km to the southeast in Oneida County, New York State. The closest extant populations of the other species range from 490-57 5 km to the southeast in New York State and/or 370 km to the southwest in the Carolinian region of southwestern Ontario. The disjunctions ar e attributed to a combination of warmer microclimate due to the abunda nt open rock surfaces and restricted specialized habitats of open and strongly fluctuating shorelines in the barrens region. All of the spec ies are rare in both Ontario and Canada and are also rare in many of t he adjacent states.