Taxonomy of Heuchera

Taxonomic arrangement of the genus Heuchera begins with Torrey and Gray, who erected sections in 1840. In 1905, Rydberg erected unranked names that were afterwards interpreted as subsections (but validated at that rank in the 1930s by Engler). Rosendahl, Butters, and Lakela, in the last genus monograph of 1936, combined these categories into a system of sections and subsections that has been used by later workers. Their sections in particular, largely based on the Torrey and Gray system, have proved artificial; the arrangement of the eastern species was much improved by E.F. Wells (1984).

The taxonomy of the genus Heuchera has recently been realigned on the basis of combined DNA and morphology (Folk & Freudenstein, 2014, in American Journal of Botany). In this paper we recognized three sections of the genus, and a tentative fourth, with two species that still could not be placed confidently. This is the taxonomy as it currently stands:

Sect. Heuchera

• • Subsect. Heuchera (= subsect. Americanae; across the eastern US)

  • H. americana

  • H. caroliniana

  • H. pubescens

  • H. alba

  • H. longiflora

  • H. richardsonii

  • Subsect. Parvifoliae (Great Basin, southern Basin and Range, northern Rockies)

  • H. parvifolia

  • H. wootonii

  • H. soltisii

  • Subsect. Novomexicanae (Southern Basin and Range)

  • H. novomexicana

  • H. glomerulata

  • H. eastwoodiae

  • H. inconstans

Sect. Rhodoheuchera

• • Subsect. Hemsleyanae (Sierra Madre of Mexico)

  • H. longipetala

  • H. acutifolia

  • H. mexicana

  • Subsect. Rosendahliae (northern Sierra Madre Occidentale)

  • H. rosendahlii

  • H. wellsiae

  • Subsect. Rubescentes

  • H. rubescens

    • H. parishii (may fit better in the following section)

  • Subsect. Elegantes (Transverse Ranges of California, and the nearby Laguna Mountains)

  • H. abramsii

  • H. elegans

  • H. caespitosa

  • H. hirsutissima

  • H. brevistaminea

    • H. pulchella (placement tentative)

  • Subsect. Sanguineae (primarily Sierra Madre Occidental, outliers in the northernmost Sierra Madre Oriental, southernmost Basin and Range)

  • H. lakelae

  • H. sanguinea

Sect. Holochloa

• Subsect. Villosae (unglaciated eastern US)

  • H. villosa

  • H. puberula

  • H. missouriensis

  • H. parviflora

• Subsect. Micranthae (Coast Ranges, Sierra Nevada)

  • H. micrantha

  • H. maxima

  • H. pilosissima

• Subsect. Cylindricae (Northern Rockies and adjacent areas)

  • H. chlorantha

  • H. cylindrica

Sect. Bracteata (tentative circumscription; mostly the Rockies, also Capitan Mountains)

• • H. bracteata

  • H. grossulariifolia

  • H. hallii

  • H. woodsiaphila

Incertae sedis

• • H. glabra

  • H. merriamii