Vascular Plants of North Carolina

Vascular Plants of North Carolina

Account for American Alumroot - Heuchera americana L.

Section 6 » Order Rosales » Family Saxifragaceae

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Author	L.
Distribution	In recent years, the very similar Heuchera caroliniana was split out from H. americana; H. caroliniana is limited mainly to the western and central Piedmont of the state. Thus, within this portion of the province, some records of H. americana may actually belong to H. caroliniana; more field and herbarium study is needed. The map below is based solely on SERNEC records from the NCU herbarium, plus a few county records shown in RAB (1968) that are from counties east of the counties where H. caroliniana has been collected. Weakley (2018) even states that "Within the range of H. caroliniana, H. americana is nearly absent." Based on the collection records on the map below, the range in NC seems to be rather disparate -- it occurs throughout the Mountains, most of the Piedmont, and much of the western and central Coastal Plain, with an appearance hiatus down the west-central Piedmont. One must wonder if there is a varietal difference between the western population and the eastern population. This is a widespread Eastern species, ranging from CT west to MO, and then south to central GA and northeastern TX.
Abundance	Fairly common to common in the Mountains and the southwestern Piedmont; generally common in the central and eastern Piedmont, but scarce to locally absent in the northwestern and west-central Piedmont. Mostly rare into the Coastal Plain, and there generally close to brownwater rivers and floodplains and other higher pH soils.
Habitat	This is a species of mostly mesic and often somewhat rocky areas. It grows best in partial shade and on soils that are circumneutral or only slightly acidic. It can occur in rich soils, but mostly where the canopy is partly open. Habitats include open forests, mesic wooded slopes especially where rocky, near rock outcrops, and a variety of other settings, even along wooded borders. The farther east the more the species requires rich, higher pH soils of Basic Mesic Forests or in forests over marl.
Phenology	Blooms from April to June, and fruits shortly after blooming.
Identification	This is, by far, the most familiar Heuchera in NC, the one that essentially all biologists have seen. However, in parts of the state -- mainly the western half, it must be identified with care. It has several basal leaves on long petioles, and each leaf blade is somewhat rounded with a cordate base; the blade is somewhat split into several lobes and with clearly serrated margins. The separate flowering stalk grows to about 2-2.5 feet tall, with the inflorescence occupying the top 6-12 inches. The flowers, scattered along this stalk, have an urn-shaped or bell-shaped calyx, as opposed to hemi-spherical in the very similar H. caroliniana. The stamens extend about 3 mm or more beyond the calyx, and the styles also extend about 2-3 mm beyond the calyx when in flower; in H. caroliniana the stamens extend barely 1 mm beyond the calyx and the styles the same. Thus, H. americana has flowers that show slightly more the tips of the stamens and styles than with the other species. These are very detailed characters that take the joy out of simply enjoying these species, even if the flowers are not colorful but are a pale white. The flowers tend to be drooping in these species, as opposed to spreading horizontally in H. acerifolia. Also beware that in leaf, this species is very similar to Foamflower (Tiarella cordifolia), which has a much more attractive and dense white panicle of flowers when in bloom. Normally, Tiarella grows in richer soil on lower slopes and can occur in moderate stands, whereas Heuchera species generally grow only singly or in small groups and on drier or rockier sites, though both can occur in the same general area.
Taxonomic Comments	There is no issue with this being a good species, but some references may still include H. caroliniana within it or as a variety. It would be little surprise if other taxa are split out from it in future years.
Other Common Name(s)	None
State Rank	S5
Global Rank	G5
State Status
US Status
USACE-agcp	FACU link
USACE-emp	FACU link

County Map - click on a county to view source of record.

Photo Gallery

photographer	comments	photo_link	county	obsType
B.A. Sorrie	Piedmont, 14 May 2016.		Richmond		Photo_natural
B.A. Sorrie	Piedmont, rock ledge by creek, 11 May 2021.