A New Species of Corallorhiza (Orchidaceae) from West Virginia, U.S.A.

Abstract

Corallorhiza bentleyi Freudenstein is described from West Virginia, U.S.A. The species is cleistogamous and is currently known from only one population. It is most similar to C. striata Lindley, specifically variety involuta (Greenman) Freudenstein from southern Mexico, particularly in the structure of the labellum and size of the flower. Corallorhiza Gagnebin comprises 11 species (including the one herein) of temperate-montane leafless orchids (Freudenstein, 1997). The genus is limited to the New World, except for C. trifida Chatelain, which is circumboreal. The centers of diversity are southern Mexico and the northeastern United States and Canada. The present taxon is currently known from only a single population but should be sought elsewhere in the region; given its cleistogamous nature, plants could be dismissed easily as individuals of the much more common C. maculata (Rafinesque) Rafinesque in bud. Corallorhiza bentleyi Freudenstein, sp. nov. TYPE: U.S.A. West Virginia: Monroe Co., ca. 43 km NW of Roanoke, Virginia, 18 July 1998, Freudenstein 2550 (holotype, AMES). Figure 1. Species Corallorhizae striatae var. involutae (Greenman) Freudenstein maxime similis, sed callo ampliore labelli et floribus cleistogamis differt. Plants to ca. 20 cm tall, reddish to yellow, with up to 20 flowers. Leaves reduced to sheaths. Rhizomes coralloid, roots absent. Flowers closed, perianth connivent, perianth segments 3-veined, those other than the labellum with very faint darker reddish striping, sometimes with yellowish perianth and reddish ovary and rachis. Dorsal sepal lanceolate, 5.9-6.1 mm long, 2.1-2.5 mm wide. Lateral sepals lanceolate, somewhat falcate, strongly cymbiform, 5.5-6.1 mm long, 2.1-2.5 mm wide. Lateral petals narrowly ovate, weakly cymbiform, acute, 5.0-5.8 mm long, 2.2-3.0 mm wide. Labellum unlobed, ovate, acute, with prominent, thickened, involute margin, 4.9-5.7 mm long, 3.1-3.5 mm wide and with slightly upturned apex; callus formed from two fused lamellae at the base of labellum, ca. 1/2 as long as the labellum, 2.5-2.8 mm long, 1.5-1.8 mm wide. Column curved forward, 3.0-3.8 mm long, 0.8-1.0 mm wide, with a small depression adaxially at its base. Rostellum triangular. Pedicellate ovary narrowly obovoid, 6.0-9.0 mm long, 2.5-3.0 mm diam., without adaxial mentum at summit. Etymology. The species is named for Stanley Bentley, of southwestern Virginia, who discovered and first recognized the distinctness of this population. This unusual Corallorhiza is known from a single population in an area ca. 4 m X 4 m on an abandoned revegetated railroad grade, with neither tracks nor ties present, in Appalachian deciduous forest of Acer pensylvanicum L., Liriodendron tulipifera L., Quercus, and Rhododendron. The population has increased in number since it was discovered in 1996. Four plants in fruit were noted that year, with eight stems in 1997, 20 in 1998, and 27 in 1999 (S. Bentley, pers. comm.). Although individuals of Corallorhiza are often clonal, the variation in color seen in this population suggests that more than one clone is present. Searches in the immediate area have not yet uncovered additional individuals. Neither were specimens detected in a monographic study of the genus (Freudenstein, 1997) or in a recent search of material at WVA. However, it seems likely that other individuals may exist, since the site was an active railroad earlier in the 20th century, and the plant could almost certainly not have been growing at its present location at that time. The species is clearly most similar to Corallorhiza striata Lindley, which is the only other species to have an unlobed labellum with involute margins, fused lamellae at the base of the labellum, and the absence of a small spur (often called a mentum) at the summit of the ovary. Corallorhiza striata is a morphologically variable species that has a wide distribution across North America. The population of C. striata nearest to the West Virginia NovoN 9: 511-513. 1999. This content downloaded from 207.46.13.60 on Thu, 21 Apr 2016 07:10:50 UTC All use subject to http://about.jstor.org/terms