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..
Erect, hairy, 6-15' high, branching. Basal and lower leaves broad-petioled, the blade 1"-2' broad and long, 3-divided or cleft, the divisions broadly ovate, cuneate, stalked, cleft and lobed, the terminal sessile or nearly so, deeply cleft into linear-oblong obtuse segments; flowers yellow, 12" broad or less; petals much exceeding the reflexed calyx; head of fruit oblong, 2"-3" thick; achenes flat, strongly margined, short-beaked, provided with a series of small tubercles or papillae which become more prominent in drying, or nearly smooth.
Ranunculus parviflorus L. Sp. Pl. Ed. 2, 78c. 1763.
Hairy, slender, diffuse, annual, branching from the base, 6'-10' high. Basal leaves long-petioled, the blade reniform or cordate-orbicular, 1' broad or less, 3-cleft, the lobes broadly oval, obtuse, cut and toothed; upper leaves short-petioled or nearly sessile, 3-5-parted into linear-oblong lobes; flowers yellow, 1"-2" wide; petals not much longer than the calyx; head of fruit globose, 2" broad; achenes flat, margined, densely papillose, 1 1/2" long, tipped with a sharp beak of about one-fourth their length.
In waste places, Maryland and eastern Virginia to Florida, Arkansas and Texas, and in ballast grounds about the northern seaports. Naturalized or fugitive from Europe. Also naturalized in Bermuda and in Jamaica. Summer.
Ranunculus muricatus L. Sp. Pl. 555. 1753.
Annual, glabrous or sparingly pubescent, branched from the base, 1°-2° high. Lower and basal leaves on long broad petioles, the blade reniform or cordate-orbicular, 1'-2' wide, 3-lobed, cleft, or crenate; the upper 3-divided, cuneate, short-petioled or sessile; flowers light yellow, 3"-5" wide, the petals exceeding the calyx; head of fruit globular, 5"-6" wide; achenes flat, with a broad smooth margin, densely muricate and spiny on the sides, 2" long, tipped with a stout slightly curved beak of one-half their length, the stout margin unarmed.
Waste places and fields, eastern Virginia to Arkansas, Florida and Texas. Bermuda. Naturalized or adventive from Europe. Also on the Pacific Coast Native also in Asia. Summer.