Deschampsia cespitosa subsp. parviflora (Poaceae) - an overlooked woodland grass

Abstract

Deschampsia cespitosa (L.) P. Beauv. subsp. parviflora (Thuill.) Dumort was, to British and Irish botanists, a little known taxon prior to1988, and current distribution mapping shows a marked geographical recording bias. It is confirmed as being primarily a woodland taxon, at low altitudes; modal mean altitude 50-75 m AOD, with 97% of locations at ≤300 m AOD. A combination of woodland or shaded habitat, bright green narrow leaves, and delicate panicle, with small spikelets, is suggestive of subsp. parviflora. In combination, degree of leaf blade scabridity on the adaxial surface, appearance of papillae on flat surfaces of adaxial ridges of the leaf, and spikelet length, provide the most reliable means of distinguishing this subspecies from subsp. cespitosa. There is no reason to suspect that subsp. parviflora is increasing, rather it had previously been overlooked.