R. Ficària, L. (representing the § Ficaria), which has tuberous-thickened roots, Caltha-like leaves, and scape-like peduncles bearing a 3-sepalous and 8–9-petalous yellow flower, has been found as an escape from gardens about New York and Philadelphia.
§ 1. BATRÁCHIUM. Petals with a spot or naked pit at base, white, or only the claw yellow; achenes marginless, transversely wrinkled; aquatic or subaquatic perennials, with the immersed foliage repeatedly dissected (mostly by threes) into capillary divisions; peduncles 1-flowered, opposite the leaves.
[*] Receptacle hairy.
1. R. circinàtus, Sibth. (Stiff Water-Crowfoot.) Leaves all under water and sessile, with broad conspicuous stipules, the divisions and subdivisions short, spreading in one roundish plane, rigid, not collapsing when withdrawn from the water. (R. divaricatus, Man., not Schrank.)—Ponds and slow streams, Maine and Vt., to Iowa, north and westward, much rarer than the next. June–Aug. (Eu.)
2. R. aquátilis, L., var. trichophýllus, Gray. (Common White Water-Crowfoot.) Leaves all under water and mostly petioled, their capillary divisions and subdivisions rather long and soft, usually collapsing more or less when withdrawn from the water; petiole rather narrowly dilated.—Common, especially in slow-flowing waters, the eastern form with more soft and flaccid leaves. June–Aug. (Eu.)
Var. cæspitòsus, DC. A dwarf terrestrial form, rooting at the nodes, the small leaves somewhat fleshy, with broader rigid divisions.—S. Ill. (Schneck), and westward.
[*][*] Receptacle glabrous; no submersed leaves.
R. hederàceus, L. Rooting freely in shallow water; leaves all reniform, angulate-lobed.—Fresh-water marshes at Norfolk, Va. (Nat. from Eu.)
§ 2. HALÒDES. Petals yellow, with nectariferous pit and scale; carpels thin-walled, striate, in an oblong head; scapose, spreading by runners.
3. R. Cymbalària, Pursh. (Sea-side Crowfoot.) Glabrous; scapes 1–6´ high, 1–7-flowered; leaves clustered at the root and on the joints of the long rooting runners, roundish-heart-shaped or kidney-shaped, crenate, rather fleshy, long-petioled; petals 5–8.—Sandy shores, from New Jersey northward, and along the Great Lakes to Ill., Kan. and westward; also at salt springs. June–Aug.