Heuchera americana var. hirsuticaulis
Heuchera americana
American alumroot
alumroot, American alum-root, common alum-root
leafy, 40–145 cm, glabrous or short stipitate-glandular.
petiole glabrous or very short to long stipitate-glandular;
blade (often variegated adaxially), broadly ovate to cordate, shallowly 5–9-lobed, 3.5–11 cm, base cordate to nearly truncate, lobes rounded or ovate, margins dentate, apex acute or obtuse, surfaces abaxially glabrous or short stipitate-glandular, adaxially glabrous or short stipitate-glandular.
densely long stipitate-glandular.
diffuse.
hypanthium free 1.1–2 mm, campanulate;
petals greenish, white, or pink, narrower than sepals, margins nearly entire or finely dentate.
hypanthium weakly bilaterally symmetric, free 0.6–2 mm, green, urceolate or campanulate, abruptly inflated distal to adnation to ovary, 3–7.2 mm, very short stipitate-glandular;
sepals erect, green-tipped, equal, 1–2.4 mm, apex rounded;
petals erect, greenish, white, pink, or purple, narrowly spatulate, unlobed, 0.9–4 mm, margins entire or finely dentate or fimbriate;
stamens exserted 3–5 mm;
styles exserted 2.6–6.4 mm, 4–7 mm, to 0.1 mm diam.
ovoid, 4–10.5 mm, beaks divergent, not papillose.
dark brown, ellipsoid, 0.6–0.9 mm.
= 14.
Heuchera americana var. hirsuticaulis
Heuchera americana
Variety hirsuticaulis occurs in a band from Oklahoma to Michigan, where var. americana and Heuchera richardsonii overlap; it is intermediate between those taxa in floral characters but is densely long stipitate-glandular like H. richardsonii. It is probably the result of introgression from H. richardsonii from as long ago as the Pleistocene migrations. Data from a breeding study involving the two species showed a tendency for the shorter hypanthium of var. americana to dominate in the artificial hybrids between H. americana and H. richardsonii (E. F. Wells 1979).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 3 (3 in the flora).
Heuchera americana is highly polymorphic and distributed over a large part of the eastern United States and Canada. Its variability is largely the result of its wide geographic range, the sporadic, semi-isolated distribution of populations, and interaction of differential adaptation and genetic drift made possible by its distribution pattern.
Heuchera americana intergrades with both H. pubescens and H. richardsonii where they overlap; the intergrading form with H. pubescens is H. americana var. hispida, and with H. richardsonii it is H. americana var. hirsuticaulis. A breeding study between H. americana, H. pubescens, H. richardsonii, and other species demonstrated ease of artificial hybridization and fertility of offspring among H. americana, H. pubescens, and H. richardsonii (E. F. Wells 1979).
Individuals of the three varieties do not form intermixed populations; populations tend to be geographically isolated from one another and to be relatively uniform, displaying somewhat narrow character variation within a population.
The Cherokee Indians took Heuchera americana for dysentery and used the powdered root for malignant ulcers, bad sores, bowel complaints, piles, female problems, and sore mouth. The Chickasaw Indians used the root as an astringent and tonic (D. E. Moerman 1998).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Petioles densely long stipitate-glandular. | var. hirsuticaulis |
1. Petioles glabrous or short to sparsely long stipitate-glandular | → 2 |
2. Petioles glabrous or very short to sparsely long stipitate-glandular; hypanthia free 0.6-1.5 mm; petals greenish, white, or pink, narrower than sepals, margins entire or finely dentate. | var. americana |
2. Petioles glabrous or very short stipitate-glandular; hypanthia free 1.5-2 mm; petals purple or pink, wider than sepals, margins fimbriate. | var. hispida |
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