The dune race of Vitis riparia in Ontario: Taxonomy, conservation and biogeography

Abstract

Although poorly known, the native dune grape, Vitis riparia Michaux var. syrticola (Fernald & Wiegand) Fernald, is a potentially important source of valuable traits for the improvement of cultivated grapes. In order to clarify its taxonomic and conservation status in Ontario and to evaluate ecological and geographic patterns, data were collected from 623 specimens from 10 herbaria. In addition, five plants referable to var. syrticola with densely hairy petioles and five referable to var. riparia with glabrous petioles were cultivated in a greenhouse under uniform mesic conditions. Although the sample was considered reliable, there was no bimodal pattern in the putatively distinctive dense pubescence to support taxonomic recognition of var. syrticola; it may be referred to simply as “the dune race.” Cultivated plants retained their initial pubescence characteristics for 3 consecutive years, suggesting that the character is relatively stable. Plants referable to the dune race with dense pubescence occurred in extremely dry and open natural habitats and occurred significantly more often than expected on shoreline sand dunes of the Great Lakes. In contrast, plants without hair or less pubescent were significantly under-represented in dry habitats and shoreline dunes. While Vitis riparia is widespread in southern Ontario, the pubescent race is restricted and has a predominantly Great-Lakes-shoreline distribution pattern. It has been reported from only 43 locations and is considered vulnerable to decline. Key words: Grape, Vitis, Ontario, germplasm protection, crop relative