Virginia Journal of Science 44: 122


A Unique Habitat for Drosera rotundifolia L. (Droseraceae) on the Blackwater River, Virginia

Philip Sheridan, Meadowview Biological Research Station and Department of Biology, Virginia Commonwealth University



Drosera rotundifolia occurs at two locations on vertical, clay seepages near Milk and Sandy Landings on the Blackwater River.  Thirty miles of river exploration between Walters and Battle Beach revealed that large, exposed, vertical, clay seepages are rare and occur in bends in the river where sand deposits of 4-7 feet overlay an impermeable clay layer.  When these conditions occur spring water is released at the contact point between sand and clay layers.  The resultant seepage over the vertical clay surface provides prime habitat for D. rotundifolia.  This type of occurrence is unknown elsewhere on the coastal plain of Virginia for this species and represents the only extant stations south of the James River.  Associated seepage species include Alnus serrulata (Aiton) Willd.,  Arundinaria gigantea (Walter) Muhl., Clethra alnifolia L., Magnolia virginiana L., Smilax laurifolia L., Sphagnum and Xyris species.