Taxonomy and Distribution of Pyrola subaphylla Maxim. (Pyroleae, Ericaceae)

Abstract

Pyrola subaphylla (Pyroleae, Ericaceae), which generally produces reddish scapes and scale-like or extremely small leaves, has been treated as a variety or form of the closely related P. japonica, which generally has green scapes and fully developed leaves, owing to observations of individuals with intermediate morphology. Recently, these two taxa were shown to differ genetically, supporting recognition of P. subaphylla as a distinct species. We identified herbarium specimens as P. subaphylla when (1) at least three shoots were mounted on the same sheet, (2) leaf blades <3.0 cm in length were present on all mounted shoots, and (3) at least one flowering shoot either lacked ordinary leaves, which are distinguished from scale-like leaves with blade >1 cm long, or bore only a single ordinary leaf. A revised taxonomic treatment of the species is proposed. In Japan, P. subaphylla occurs in Hokkaidō, Honshū (Tōhoku and Chūbu district), and Shikoku, usually in coniferous forests at 0–1,500 m.