*Ficaria Schaeffer. Subfamily: Ranunculoideae. Tribe: Ranunculeae.
A genus of about 5 species, herbs, of Europe west to c. Asia. Best treated as a genus separate from Ranunculus, based on morphology and molecular phylogenetics; Myosurus is (for instance) more closely related to Ranunculus than is Ficaria (Paun et al. 2005; Emadzade et al. 2010). Post et al. (2009) analyze the presence in North America of the various infrataxa recognized in Europe and find evidence that all are naturalizing. The species is reported to be developing into a seriously invasive species in ne. United States and adjacent Canada (Axtell, DiTommaso, & Post 2010) and increasingly as well in at least the more northern or montane parts of our area.
ID notes:When in flower, Ficaria is sometimes confused with the superficially similar Caltha. Ficaria has both yellow petals and (usually 3) green (or greenish yellow) sepals, whereas Caltha has only yellow sepals and no green (sepaloid) structures. The yellow petals of Ficaria are oblong, > 2× as long as wide, whereas the yellow petaloid sepals of Caltha are broadly ovate, obovate, or orbicular, < 1.5× as long as wide. Ficaria has entire leaves, while Caltha has a strongly toothed leaf margin. The utility of attempting to recognize the multiple European subspecies in the United States is questionable.
Ref: Axtell, DiTommaso, & Post (2010); Banfi, Galasso, & Soldano (2011); Emadzade et al. (2010); Paun et al. (2005); Post et al. (2009); Sell (1994); Stace (2010); Tamura In Kubitzki, Rohwer, & Bittrich (1993); Whittemore (1997a) In Flora of North America Editorial Committee (1997). Show full citations.