Rhododendron Linnaeus. Rhododendron, Azalea.
A genus of about 860 species, shrubs and trees, mostly north temperate (centered in Himalayan Asia). Molecular evidence appears to show that Menziesia should be included in Rhododendron, and is actually closely related within Rhododendron to R. vaseyi (Goetsch, Eckert, & Hall 2005; Kurashige et al. 2001); while the urceolate corolla is rather anomalous in Rhododendron, many other morphological characters do ally Menziesia with "basal" clades in Rhododendron s.l.
Considerable additional work is needed to clarify Rhododendron taxonomy in our region. A new species in the "Punctatum complex" is in the process of being described. Additional entities appear to warrant recognition in the "Viscosum complex" and the "Canescens complex"; these will be more thoroughly tackled in the next edition.
ID notes: This key makes as much use as possible of vegetative characters, geography, and capsule characters; capsules are generally available for longer during the year than flowers, and even when plants are in flower, last year's capsules can often be found.
Ref: Albach & Bauer (2021); Chamberlain (1982); Craven (2011); Cullen (1980); Davidian (1982); Duncan & Pullen (1962); Fabijan (2009a) In Flora of North America Editorial Committee (2009); Goetsch, Eckert, & Hall (2005); Horn (2019); Judd & Kron (1995); Judd & Kron (2009a) In Flora of North America Editorial Committee (2009); Kron (1993); Kron & Creel (1999); Kurashige et al. (2001); Miller (2011); Miller (2012); Stevens et al. In Kubitzki et al. (2004); Towe (2004); Wilson & Rehder (1921); Zhou et al. (2008). Show full citations.