Hexastylis is a genus of low-growing, evergreen perennial herbs in the family Aristolochiaceae (the birthwort family), order Piperales. Native to North America — and concentrated in the southeastern United States — the genus comprises approximately ten species of woodland plants closely allied to wild ginger (Asarum).
Plants grow from creeping rhizomes just beneath the soil surface and produce distinctive kidney- to arrowhead-shaped leaves that are often mottled or variegated with silver-green patterning, remaining persistent through winter. Like other members of Aristolochiaceae, Hexastylis bears small, jug- or urn-shaped flowers in spring, produced singly at the base of the leaves; the flowers are inconspicuous above ground but are pollinated at or near soil level. The genus contains aristolochic acid, a nephrotoxic carcinogen present across Aristolochiaceae, and should not be consumed.
The taxonomic placement of Hexastylis has been debated for over a century. The genus was established primarily through the work of H.L. Blomquist, who segregated it from Asarum based on chromosome number and floral morphology. Subsequent molecular studies of the nuclear ribosomal ITS region, combined with morphological data, suggest that Hexastylis as traditionally circumscribed is not monophyletic: some species appear more closely related to Asiatic Heterotropa than to other North American members of the group. Many contemporary treatments therefore subsume Hexastylis within a broadly defined Asarum, while regional botanists in the southeastern United States often continue to recognize it at generic rank. GBIF accepts Hexastylis as a distinct genus within Aristolochiaceae.
Representative species include Hexastylis arifolia (litterbrown jug), Hexastylis speciosa, and Hexastylis virginica, all valued as shade-tolerant groundcovers in native plant gardens.
Etymology
The name Hexastylis derives from the Greek hex (six) and stylos (pillar or style), referring to the six stylar columns characteristic of the flowers in this group, distinguishing them from related genera. The genus was formally recognized by botanist H.L. Blomquist.
Distribution
Hexastylis is endemic to North America, with all species concentrated in the eastern and southeastern United States. The genus occupies moist, shaded forest understory habitats, particularly in the Appalachian region and the coastal plain of the Southeast.
Ecology
Hexastylis species grow in moist, shaded forest sites with humus-rich soil, typically as understory plants in deciduous and mixed woodland. Their persistent, patterned leaves allow photosynthesis year-round in low-light conditions. Flowers are borne near the soil surface in spring and are likely pollinated by fungus gnats or other ground-level insects attracted to the jug-shaped perianth.
Taxonomy Notes
Hexastylis has long been treated as either a distinct genus or as section Hexastylis of a broadly circumscribed Asarum. H.L. Blomquist's monograph established generic rank based on chromosome number and floral characters. However, ITS-based phylogenetic analyses indicate the group is likely paraphyletic: certain Hexastylis species are more closely related to the Asiatic Heterotropa than to one another, and the morphological characters used to support generic recognition are plesiomorphic with respect to other Asarum lineages. GBIF currently accepts Hexastylis as a valid genus in Aristolochiaceae.
Cultivation
Hexastylis species are grown as shade-tolerant groundcovers in native plant and woodland gardens, particularly in the southeastern United States. They prefer moist, well-drained soils rich in organic matter and perform well under deciduous canopy. Their attractive, persistent, often silver-patterned foliage makes them ornamentally appealing. Plants spread slowly by rhizome and tolerate deep shade. They should not be ingested, as Aristolochiaceae members contain aristolochic acid.
