Flora of North America species comparison

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Heuchera americana var. americana

Heuchera americana var. hirsuticaulis
Photo is of parent taxon

American alumroot
Photo is of parent taxon

American alumroot
Petioles

glabrous or very short to sparsely long stipitate-glandular.

densely long stipitate-glandular.
Flowers

hypanthium free 0.6–1.5 mm, urceolate;

petals greenish, white, or pink, narrower than sepals, margins entire or finely dentate.

hypanthium free 1.1–2 mm, campanulate;

petals greenish, white, or pink, narrower than sepals, margins nearly entire or finely dentate.
2n

= 14.

= 14.

Heuchera americana var. americana

Heuchera americana var. hirsuticaulis
Phenology Flowering Apr–Jun. Flowering Apr–Jun.
Habitat Rich woods often over base-saturated granite and gneiss, or in shallow, rocky soil Rich woods or open grasslands often over base-saturated granite and gneiss, or in shallow rocky soil
Elevation 70-1300 m (200-4300 ft) 200-400 m (700-1300 ft)
Distribution
from FNA
AL; AR; CT; DE; GA; IL; IN; KY; LA; MD; MI; MO; MS; NC; NJ; NY; OH; OK; PA; SC; TN; VA; WV; ON
[BONAP county map]
from FNA
AR; IL; IN; MI; MO; OK
[BONAP county map]
Discussion

Variety americana is widely distributed from Connecticut to Georgia and from southern Ontario and Ohio to Oklahoma and northwestern Louisiana. It intergrades with Heuchera pubescens and H. richardsonii where their ranges overlap, but not with H. longiflora, H. parviflora, or H. villosa, which also share overlapping ranges with it.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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.)
Source FNA vol. 8, p. 94. FNA vol. 8, p. 95.
Parent taxa Saxifragaceae > Heuchera > Heuchera americana Saxifragaceae > Heuchera > Heuchera americana
Sibling taxa
H. americana var. hirsuticaulis, H. americana var. hispida
H. americana var. americana, H. americana var. hispida
Synonyms H. americana var. brevipetala, H. americana var. heteradenia, H. americana var. subtruncata, H. calycosa, H. curtisii, H. curtisii var. crenata, H. lancipetala H. hispida var. hirsuticaulis, H. americana var. interior, H. hirsuticaulis
Name authority unknown (Wheelock) Rosendahl: Minnesota Stud. Pl. Sci. 2: 60. (1936)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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