A genus of about 750 species, perennials, nearly cosmopolitan. The southeastern North American flora is not especially rich in number of species, but includes a large number of the clades in the genus (Xu et al. 2020). The clades and subclades shown in the key are from Xu et al. (2020).
ID notes: Several of the more frequently encountered sterile (to partly fertile) hybrids are included in the key and treated fully below. Rarer and solely sterile hybrids may be recognized by intermediate morphology and usual co-occurrence with both parents.
Ref: Heo et al. (2022); Heo, Yun, & Fernando (2023); Keener & Davenport (2007); Kessler & Smith (2018); Kramer & Viane In Kramer & Green (1990); Lin & Viane in FoC (2013) In Wu, Raven, & Hong (2013); Moran (1982); Morzenti & Wagner (1962); Murakami et al. (1999); Taylor, Mohlenbrock, & Burton (1976); Wagner, Moran, & Werth (1993) In Flora of North America Editorial Committee (1993b); Xu et al. (2020). Show full citations.