Wild buckwheat: ID it, grow it, feed bees

A wild buckwheat is a shrub, mat or cushion in the genus Eriogonum, native to western North America and grown for its late-summer flowers, not for grain. The buckwheat you eat is a different plant entirely, Fagopyrum esculentum, an annual from Asia with soft stems and white or pink flowers, unrelated to Eriogonum despite the shared common name. The two are not even in the same family: Fagopyrum sits in the Polygonaceae, and Eriogonum does too, but the resemblance stops at the flower shape, a small cup of six tepals that both genera happen to share.

1. What is a wild buckwheat, and how does it differ from the buckwheat grain we eat?

A wild buckwheat is a plant in the genus Eriogonum, the largest genus in the buckwheat family in North America, with something over 250 species described. Most are perennial, many are woody at the base, and a few are annuals that appear after winter rain and vanish by June. They grow from the plains to the alpine, but the greatest concentration is in the dry West: the Great Basin, the Mojave, the California chaparral and the sagebrush country of the Columbia Plateau.

The grain buckwheat is Fagopyrum esculentum, domesticated in Asia and grown as a summer annual crop. Its seed is ground for flour or eaten as groats. No Eriogonum is grown for grain. The seeds are small, and the plants are not cultivated at field scale. The common name came across because the flowers and the triangular seeds of Fagopyrum resemble those of the European Fagopyrum relatives that early settlers knew, and the name was simply transferred to the American genus when botanists began describing it.

A practical difference for a gardener: Fagopyrum wants moisture and dies at frost. Eriogonum wants the opposite. It resents summer water and lives for years. The journal that follows the genus in detail, The Umbel Journal, treats the two as separate subjects and keeps the food crop out of its plant portraits.

2. How do you identify a wild buckwheat on a hike?

Start with the involucre. This is the single most reliable character, and it is what separates Eriogonum from the other white-flowered shrubs you will meet on the same hillside. An involucre is a small cup of fused bracts, usually bell-shaped or top-shaped, that sits at the base of each flower cluster. In Eriogonum the involucre is conspicuous, often ribbed or angled, and it holds a cluster of flowers that opens from the center outward. In Eriogonum the involucre is the structure you can see with the naked eye, and once you have seen a few you will not confuse it with anything else.

Look at the flowers next. Each flower is tiny, six-parted, and usually white, cream, yellow or pink. They are arranged in clusters called heads or umbels, and the whole arrangement sits above the leaves on a stalk that may be leafless or nearly so. The color often shifts as the flowers age: sulfur buckwheat, Eriogonum umbellatum, opens yellow and fades to orange or red, which is why a single plant can look like two species in the same week.

Leaves come third. Most wild buckwheats have leaves in a basal rosette or clustered at the base of the stems. The leaf shape ranges from round to spoon-shaped to narrowly lance-shaped, and the surface is often woolly or hairy, especially underneath. The hairs are a real field character: they reflect light and give the plant a gray or silvery cast that stands out against the darker green of adjacent shrubs. California buckwheat, Eriogonum fasciculatum, has narrow, needle-like leaves in whorls along the stem, which is unusual in the genus and makes it easy to name once you know it.

Habit is the last check. Wild buckwheats grow as mats, cushions, subshrubs or rounded shrubs. Saint Catherine's lace, Eriogonum giganteum, is the giant of the genus and can reach two meters on the Channel Islands and in coastal gardens. Most others stay under half a meter. If you are on a sagebrush hillside in July and see a low gray shrub with cream flower heads and a small cup at the base of each cluster, you are almost certainly looking at an Eriogonum.

3. Which buckwheat should a small dry garden start with?

Start with sulfur buckwheat, Eriogonum umbellatum. It is the most forgiving species in the genus for a gardener who has never grown one. It is widely available from native plant nurseries, it tolerates a range of soils from gravel to clay if drainage is reasonable, and it survives on rainfall alone once established in most of the West. The flowers open yellow in late spring and hold for weeks, and the low mats or small mounds stay compact without shearing.

If you garden in California, Eriogonum fasciculatum is the second plant to try. It is faster than sulfur buckwheat, it takes heat and reflected light, and it is the species most often used in pollinator plantings because its long summer bloom overlaps with the flight season of native bees and butterflies. It can be cut back hard in late winter to keep it from going woody and open.

A third option for a small garden is Eriogonum grande var. rubescens, a compact form with pink to red flowers that stays under half a meter and works well at the front of a border. It is less cold-hardy than sulfur buckwheat, so it suits coastal California and mild inland sites rather than the high desert.

Whichever you choose, plant in fall, not spring. Fall planting lets the roots establish through winter rain before the first dry summer. Do not amend the soil with compost or fertilizer. Do not water after the first summer. The single most common cause of death in cultivated Eriogonum is summer irrigation, which rots the crown. If you must water, water once a month at most, and only in the first year.

4. What lives on the flowers?

The late-summer bloom of Eriogonum is one of the few reliable nectar sources in the dry West after the spring annuals have gone. Native bees, including sweat bees and mining bees, work the flower heads through July and August. Butterflies, among them the Mormon metalmark and the common hairstreak, use the plants for nectar and, in some species, as a larval host. Hummingbirds visit the taller species, especially Eriogonum giganteum and Eriogonum arborescens, where the flower clusters are large enough to give a bird a perch and a drink.

The relationship is not incidental. A dry garden planted with buckwheats is a late-season resource in a landscape where late-season resources are scarce. That is the argument for planting them even if you never look at the flowers closely.

5. Where to read more about the genus

The genus has been mapped in detail by botanists, above all James L. Reveal, whose treatments in Flora of North America and in the Harvard Papers in Botany remain the standard reference for Eriogonum taxonomy. The Eriogonum Society, a membership organisation, published newsletters and ran a seed exchange for many years; it now publishes at eriogonum.community. The Umbel Journal, an independent field journal at eriogonum.org, covers the plants, their cultivation and the insects that depend on them, and describes the society and every nursery it mentions in the third person.

For a hiker who wants to put a name to a gray shrub on a sagebrush hillside, the sequence is simple: find the involucre, check the flower color, then look at the leaves. For a gardener, the sequence is simpler still: plant sulfur buckwheat in fall, leave it alone in summer, and watch what arrives.