Spiranthes stylites is Another Long Overlooked Asian Spiranthes with an Unusual Sylvan Habitat

Abstract

Abstract— We reexamine the taxon Spiranthes stylites, currently synonymized under S. australis, finding multiple lines of evidence from molecular phylogenetics, phenology, morphology, and habitat differences to support its distinction from other members of the Spiranthes sinensis species complex. Compared to its closest relative S. australis, S. stylites blooms earlier (June ‐ early July vs. mid July ‐ September), has consistently white tubular flowers (vs. commonly pink and pseudocampanulate), a distinctly long-clawed labellum (vs. shortly clawed), slender labellum nectar callosities (vs. globose), a proportionally larger column foot (ca. 50% of the length of the entire column vs. ca. 25%), and occurs in closed canopy woodlands (vs. open graminoid habitats). Spiranthes stylites is the only Spiranthes in the Eastern Hemisphere to have a woodland habitat. The recognition of S. stylites helps support white colored flowers as the plesiomorphic and most common floral condition in the complex, and indicates pink colored flowers likely arose independently in S. australis and S. sinensis s.s.