An astounding number of species populate the wild buckwheat genus Eriogonum — more than 250, according to the Cal Flora website. And, because of their propensity to hybridize, active speciation continues as we speak. There are species for almost every letter of the alphabet, from A (E. abertianum) to Z (E. zionis).
This article will discuss characteristics common to all of the wild buckwheats, and then focus on a landscape beauty, E. giganteum, known familiarly as St. Catherine’s Lace or giant buckwheat.
But first, let’s address a common question: Do the wild buckwheats native to North America supply the gluten-free buckwheat flour used in pancakes and other baked goods? The answer is no.
Although young stems and leaves from our wild buckwheats were eaten by Native Americans, the buckwheat flour we bake with today is a product of the cultivated European common buckwheat, Fagopyrum esculentum. Both genera are in the same family, Polygonaceae.
To further complicate matters, another plant in that family, Fallopia convolvulus or black-bindweed, is also called wild buckwheat. This is where taxonomic nomenclature is so very helpful in plant identification, if not always user friendly.
And the last bit of fun with words involves etymology. The Latin genus name Eriogonum was bestowed by French botanist and explorer André Michaux, who traveled to the United States in 1785 to find plants that could be taken back to France for use in carpentry, medicine and agriculture.
During his botanical explorations in the Southeastern US, he came upon a wooly plant with sharply bent stems and christened it Eriogonum tomentosum (common name dogtongue wild buckwheat). Eriogonum translates from the Greek as “wooly knees” (erion equals wool and gona equals knee or joint); tomentosum translates from the Latin as densely matted or hairy, a descriptor originally used for plants that were used to stuff mattresses or pillows.
Wild buckwheats have mastered the art of thriving in the multiple challenging environments found in California. In a 2013 article for Pacific Horticulture, local garden guru Jennifer Jewell notes that these hardy dryland natives “thrive in exposed locations on slim soils” and “are at their best in lean, well-draining soil and full sun.”
She quotes international buckwheat expert James Reveal, who marvels at this plant’s ability to inhabit any ecological habitat, from “the seashore to the highest mountains in the United States.” He says that, “They are among the last plants seen atop the Sierra Nevada and on the ‘outskirts’ of Badwater in Death Valley.”
Not content to just colonize tough niches in our state, wild buckwheats provide crucial late summer food for pollinators. They continue to flower after other natives have become dormant to protect themselves from drought and heat. Jewell observes that buckwheats “reliably attract a whole symphony of pollinators including native bees, wasps, flies, butterflies, beetles and birds.”
St. Catherine’s lace (Eriogonum giganteum) is one of the many buckwheat species that provide food to a wide variety of pollinators; it is also a beautiful landscape plant, especially for larger spaces. Its species name, giganteum, reveals its claim to fame; this is the largest of all the wild buckwheats, with the ability to grow up to ten feet high and wide.
It prefers fast-draining rocky soil but will tolerate heavier clay soils if seldom watered and can also handle alkaline conditions. Although this species is native to California’s Channel Islands, it easily adapts to summer temperatures in the Valley, and will withstand winter lows of 15 to 25 degrees Fahrenheit.
Depending on conditions, St. Catherine’s lace can flower from May through August (one source claims it can bloom until December). The bloom consists of large, dense, flat clusters made up of many small white or pinkish flowers which turn reddish-brown later in the season.
The plentiful flowers attract a variety of pollinators, including native bees, pollinator flies, wasps and several species of butterflies. St. Catherine’s lace is what is known as a “honey plant” which means that honeybees collect its nectar for making honey. Finches and other migratory birds feast on its seeds in the fall. And large mature plants offer sheltering habitat to birds and lizards.
The leathery, woolly, oval-shaped leaves are large relative to other wild buckwheat species and range from a grayish green to silver. Occasional summer water will keep this buckwheat evergreen, but in the wild, plants will drop a portion of their leaves as a drought survival strategy.
Endemic to the Channel Islands of Southern California, St. Catherine’s Lace naturally populates coastal sage and chaparral ecoregions. Three distinct species have developed on three of the eight Channel Islands: Santa Barbara Island buckwheat (var. compactum); San Clemente Island buckwheat (var. formosum); and Santa Catalina Island buckwheat (var. giganteum).
As an ornamental landscape plant, it is at its best in native plant, drought tolerant, and wildlife gardens, and when a natural garden design is desired. Its size, form, and texture make it a good choice for background planting, or to fill and soften a bare corner in the yard. The UC Davis Arboretum classifies E. giganteum as one of its “All-Stars” a testament to this plant’s aesthetic value and endurance in our hot, dry landscape, and its service to native pollinators and other wildlife.
Each of the 256 species in the genus Eriogonum offers its own version of habitat value and native beauty. Visit the Cal Flora website at www.calflora.org to view detailed photos of each of the wild buckwheats and decide which is your favorite.
For more information:
Jennifer Jewell, “Beneficial Buckwheats,” Pacific Horticulture Newsletter, April 2013: https://www.pacifichorticulture.org/articles/beneficial-buckwheats/
Mother Nature’s Backyard blog: http://mother-natures-backyard.blogspot.com/2013/08/plant-of-month-august-st-catherines.html
Cal Flora Species List: https://www.calflora.org/cgi-bin/specieslist.cgi?where-genus=Eriogonum
The UC Master Gardeners of Butte County are part of the University of California Cooperative Extension system, serving our community in a variety of ways, including 4-H, farm advisers, and nutrition and physical activity programs.