Brunnichia is a monotypic genus of flowering plants in the family Polygonaceae, order Caryophyllales, comprising a single species: Brunnichia ovata, commonly known as redvine, American buckwheat vine, or ladies' eardrops. The genus is native to the south-central and southeastern United States.
Brunnichia ovata is a semi-woody deciduous vine with an alternate arrangement of simple, ovate leaves ranging from 2 to 5 inches in length. The proximal portions of the stems are woody while the distal shoots remain herbaceous. Small, greenish flowers appear from June to July, and the distinctive pendulous fruits — which give the plant its "ladies' eardrops" common name — hang in a manner reminiscent of drop earrings. Plants can climb or scramble to heights of up to 40 feet.
The species grows in lowland habitats including riverbanks, lake margins, wet woods, and thickets, primarily at elevations from sea level to 200 meters. It exhibits thigmotropism, developing tendrils that coil around supporting structures as climbing vines do. Germination requires warmth, with an optimum temperature of 35 °C.
Within its native range, redvine is valued by beekeepers as a nectar source, but it is also a notable agricultural weed — particularly in soybean crops in the Mississippi Delta region. The genus was first described under the name Rajania ovata by Thomas Walter in Flora Caroliniana (1778) and was re-circumscribed into Brunnichia by Lloyd Shinners in 1967.
Etymology
The genus name Brunnichia honors the Norwegian naturalist Morten Thrane Brünnich (1737–1827). The sole species epithet, ovata, is Latin for "egg-shaped," referring to the shape of the leaves.
Distribution
Brunnichia ovata is native to the coastal plains of the south-central and southeastern United States, ranging from Texas and Oklahoma east to Georgia and Alabama, and north to southern Illinois. It is absent from higher elevations, occurring from sea level to approximately 200 meters.
Ecology
Redvine grows in moist lowland habitats — riverbanks, lake margins, wet woods, and thickets. It is a climbing vine that uses thigmotropism (touch-sensitive differential growth) to coil tendrils around supporting structures. The species is a favored nectar plant for honeybees and is a significant weed pest in soybean crops in the Mississippi Delta.
Taxonomy Notes
The only species in the genus, Brunnichia ovata, was originally described as Rajania ovata by Thomas Walter in his Flora Caroliniana (1778). It was transferred to the genus Brunnichia by the American botanist Lloyd Shinners in the journal Sida in 1967. GBIF places the genus in the family Polygonaceae, order Caryophyllales.
Cultural Uses
Redvine is valued by beekeepers in the southeastern United States as a nectar source for honey production. In 2019, damage to native wildflowers from the herbicide Dicamba was cited as threatening this source, with the owner of an Arkansas honey producer naming redvine specifically as an example of vegetation loss leading to inferior honey quality.
