8624 Petasites Mill.
- Mill., Gard. Dict. Abr., ed. 4: no. 3 (1754).
- Nardosmia Cass. in F. Cuvier, Dict. Sci. Nat., ed. 2, 34: 186 (1825).
Notes: Korobkov, Murray, and Elven: Korobkov (PAF proposal) accepted Petasites s. lat. as one genus. Löve and Löve (1975a, 1976a) recognized three genera: Endocellion (x = 7) kept apart on morphological and ploidy criteria, and Petasites s. str. and Nardosmia (both with x = 10, supposedly) kept apart on morphological criteria. Endocellion was suggested to be closer to Tussilago.
We accept Endocellion (see Toman 1972) but not the split between Petasites s. str. and Nardosmia. Hybridization with production of 'hybrid species' is reported between their species (Nardosmia palmata x Petasites sagittatus = P. x vitifolius, see Bogle 1968). A thorough study of the North American plants is Cherniawsky and Bayer (1998a, 1998b, 1998c). These authors suggested that the variation probably is of very recent origin. They did not find reason to recognize more than one northern species with races. This became the treatment of Bayer et al. (2006) for Flora of North America. We tentatively retain P. sagittatus and its hybrid with P. frigidus (P. x vitifolius) as species below but are ready to reconsider.
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Source: Stan Shebs at Wikispecies
