This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
R. cardiophyllus Hook. Fl. Bor. Am. 1: 14. 1829.
Erect, 4'-15' high, simple or usually sparingly branched. Basal leaves long-petioled, orbicular to ovate or oblong-ovate, mostly 1'-1 1/2' broad, coarsely crenate, incised or shal-lowly lobed, those of the stem short-petioled or nearly sessile, deeply lobed or parted, the lobes narrow, mostly acute or acutish; flowers yellow, larger than in R. pedatifidus, 8"-10" broad, the petals much exceeding the densely tomentose calyx; head of fruit cylindric or ovoid-cylindric, 6"-8" long; achenes subor-bicular, slender-beaked, finely hairy.
Ranunculus Alleni Robinson, Rhodora 7: 220. 1905.
Sparingly pubescent, 4'--8' high, usually branched. Basal leaves long-petioled, orbicular to reniform, 7"-n' wide, coarsely crenate or incised, broadly cuneate to subcordate at the base; cauline leaves sessile or nearly so, deeply cleft or parted into 3-5 mostly oblong or elliptic segments; flowers bright yellow, 5 1/2" - 6 1/2" broad, the petals broad, not twice exceeding the loosely villous calyx; head of fruit ovoid to oval; achenes obliquely obovoid, glabrous, minutely beaked.
In moist grounds, Quebec. Aug. Confused with R. pedatifidus in our first edition.
Pubescent, branching, 6'-18' high. Lower and basal leaves oval, oblong, or ovate-oblong, long-petioled, the blade 1' in length or more, crenate or slightly lobed, obtuse, the base more or less cuneate, rarely subcordate; upper cauline leaves sessile or short-petioled, deeply divided into 3-7 linear or oblong obtuse lobes; flowers yellow, 9"-12" broad, the petals narrow and much exceeding the calyx; head of fruit spherical; carpels and achenes oval or orbicular, minutely beaked.
Ranunculus abortivus var. Harveyi A. Gray, Proc.
Glabrous, stem erect, slender, branched, 8'-18' tall, from a cluster of narrowly fusiform roots. Leaves thin, the basal and lower ones long-petioled, reniform or suborbicular, obtusely crenate or somewhat lobed, 5"-18" wide, cordate, or some of them truncate at the base, the upper sessile or nearly so, deeply 3-cleft or 3-parted into linear or narrowly oblong entire or few-toothed obtuse segments; flowers bright yellow, 6"-9" broad; petals 4-8, oblong, 4 or 5 times as long as the reflexed sepals; head of fruit globose, 2" in diameter; achenes oblique, compressed, tipped with a minute straight beak.
On dry hillsides, Missouri and Arkansas. April-May.