Plant of the Week
Crisp-leaf wild buckwheat (Eriogonum corymbosum)
By Walter Fertig
In the United States, crisp-leaf wild buckwheat (Eriogonum corymbosum) ranges from southern Wyoming to Nevada, Arizona, and New Mexico. Across this relatively modest range, the species is surprisingly variable in flower color, leaf shape and pubescence, and growth form. James Reveal recognizes 8 distinct varieties in his 2005 treatment of the buckwheat family (Polygonaceae) for the Flora of North America series. Stan Welsh treats the species even more broadly in A Utah Flora by including several closely related shrub and sub-shrub species that tend to intergrade and possibly hybridize with E. corymbosum.
Why is there so much variability in this species, especially compared with many others? Most varieties of E. corymbosum have white flowers that turn pink with age, while others typically have yellow flowers. Individuals within many populations may vary from white to yellow, suggesting that the trait may be based on inheritance of dominant or recessive genes. Other characteristics, such as leaf length and overall growth form may be influenced by environmental conditions. Several corymbosum varieties are restricted to unusual habitats or geologic substrates, suggesting that they have become reproductively isolated and are traveling down a new evolutionary path. Other variations may be the influence of hybridization with closely related species, such as E. thompsoniae, E. lonchophyllum, and E. brevicaule. Regardless of their origin, the populations of crisp-leaf wild buckwheat in the west are still actively evolving.
The most common form of crisp-leaf wild buckwheat (var. corymbosum) is a multi-branched shrub with branches up to 3 feet tall that form a rounded mound. The outer rim of the mound is covered by an intricately branched inflorescence of white flowers that bloom from July to October. After flowering, the fruits and branches turn bright red and persist into the winter. Due to its showy appearance and ease of cultivation-it requires little water once established-crisp-leaf wild buckwheat is becoming an increasingly popular garden plant in the southwest. The shrubs are relatively slow growing however.
Native Americans utilized crisp-leaf wild buckwheat in numerous ways. Boiled leaves and stalks were mixed with cornmeal for bread or with salt for a dried cake. Leaves were also prepared to treat coughs and tuberculosis.