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..
Heuchera parviflora Bartl. Ind. Sem. Hort.
Gotting. 1838. - Linnaea 13: Litt. 96. 1839. H. Rugelii Shuttlw.; Kunze, Linnaea 20: 43.
Stems slender, 6'-24' long, weak, glandular-hirsute or villous, leafless or bearing a few leaves below. Basal leaves with long slender glandular-villous petioles, broadly reniform, 2'-5' wide, cordate at the base, with 7-9 broad rounded or rarely pointed lobes, crenately toothed, the teeth mucronate; inflorescence very loosely paniculate; flowering calyx regular, campanulate, about 1" long; petals linear-spatulate, 2-3 times as long as the calyx-lobes; stamens somewhat exserted.
H. puberula Mackenzie & Bush, Rep. Mo. Bot. Gard. 16: 103. 1905.
Stems very slender, 4'-12' long, puberulent, leafless. Basal leaves with very slender puberulent petioles, suborbicular to reniform, 1'-2 3/4' wide, shal-lowly or deeply cordate at the base, with 5-9 rounded lobes and broad mucronate teeth, finely pubescent on both sides; inflorescence lax, few- or many-flowered; flowering calyx regular, campanulate or turbinate, about 1" long, the lobes broader and the tube relatively shorter than in H. parviflora; petals spatulate or linear-spatulate, about twice as long as the calyx-lobes; stamens exserted.
On bluffs, Kentucky and Missouri. July-Oct.
H. villosa Michx. Fl. Bor. Am. 1: 172. 1803.
Stem erect, leafless, or rarely bearing a few small leaves below, generally villous-pubescent with brownish hairs, as are also the long petioles and the veins on the lower surfaces of the leaves. Basal leaves 3'-5' wide, ovate to orbicular, sharply or obtusely and deeply 7-9-lobed, the lobes dentate or serrate, the terminal lobe usually longer than wide; flowering calyx 1"-1 1/2" long, campanulate, regular; petals linear-spatu-late, white or nearly so, twice as long as the calyx-lobes or more; stamens much exserted.
H. macrorhiza Small, Bull. Torr. Club 25: 466. 1898.
Stem erect, usually leafless, stout, from a very thick scaly rootstock, densely villous or hirsute-villous with usually sordid hairs. Basal leaves, 3'-8' wide, suborbicular in outline, shallowly lobed, with the terminal lobe usually wider than long, the teeth broad, mucronate; flowering calyx short-hairy, often larger than in H. villosa, regular; petals linear or nearly so, about twice as long as the calyx-lobes or less; stamens much-exserted.
On bluffs and river banks, West Virginia, Kentucky and Tennessee. July-Oct.
Heuchera crinita Rydb., from Kentucky and adjacent states, seems to be a robust form of H. macrorhiza.