Wild buckwheat: what it is and how to know it

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

A wild buckwheat is any plant in the genus Eriogonum, which belongs to the knotweed family, Polygonaceae. The genus is large and mostly western: it runs from the Great Plains to the Pacific coast and from Canada into Mexico, with the greatest concentration of species in California and the Great Basin. Growth forms range from low mats a few centimetres high to rounded shrubs more than a metre across, and from short-lived perennials to long-lived woody subshrubs.

How do you identify a wild buckwheat on a hike?

Identification rests on three features taken together: the involucre, the flower arrangement, and the leaves. The involucre is the most reliable of the three and the one worth learning first.

Which buckwheat should a small dry garden start with?

For a small dry garden, the practical starting point is a species that is locally appropriate, widely available, and forgiving of a first summer. Three species are commonly recommended for beginners, and each suits a different situation.

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, a group of shrubs, subshrubs and perennials native to western North America and concentrated in dry, open country. It is not the same plant as the buckwheat grown for grain, which is an unrelated crop in the genus Fagopyrum and a member of the knotweed family. The two share a common name and little else: one is a native wildflower of sagebrush hillsides, the other an Old World crop milled into flour. The distinction matters before anything else, because a reader who searches for buckwheat and lands on a seed packet may be holding a crop, not a hillside plant. The grain crop, Fagopyrum esculentum, is an annual grown in fields and harvested for its triangular seeds. Wild buckweats of the genus Eriogonum are perennials or shrubs, they are not harvested for flour, and their value in the garden is ecological rather than agricultural. The field journal on wild buckwheats treats the genus on its own terms, as a subject for gardeners, hikers and native plant walkers rather than for farmers.

The grain buckwheat sold as flour is Fagopyrum esculentum, an annual domesticated in Asia and grown as a pseudocereal. It is in the same family as Eriogonum but in a different genus, and it is not native to North America. Its seeds are eaten; the seeds of Eriogonum are small, winged or angled, and are not a food crop. A useful rule for the reader: if the plant is in a farm field and the seed is being harvested for milling, it is Fagopyrum. If the plant is on a dry slope, a road cut or a rocky ridge in the western United States, and it has tiny flowers packed into dense heads, it is very likely an Eriogonum.

How do you identify a wild buckwheat on a hike?

### The involucre

In Eriogonum, the flowers are not borne singly. They are grouped inside a small cup-like structure called an involucre, and the involucre is what gives the genus its name: erio- for wool, gonu for knee or joint, a reference to the jointed, often hairy stems of the type species. Each involucre holds one to many tiny flowers, and the involucres are themselves arranged in heads, umbels or spikes. A hand lens helps, but the shape is often visible to the naked eye: a small cup, sometimes ribbed, sometimes hairy, sometimes with a fringe of tiny teeth around its rim. No other common western shrub groups its flowers in quite this way.

### Flowers

The individual flowers are small, usually a few millimetres across, and typically have six tepals rather than distinct petals and sepals. Colour runs from white and cream through yellow, pink and red. In many species the flowers are not the showiest part: the colour that draws the eye often comes from the involucres or from the calyx, and in some species the whole flowering head turns a rusty or pinkish tone as it ages. Flowering is typically late spring through autumn, with a pronounced peak in late summer when most other shrubs have finished.

### Leaves

Leaves are usually arranged in a basal rosette or clustered at the base of the stems, and they are often woolly or hairy, especially underneath. The leaf shape varies widely: oval, round, arrow-shaped, or narrow and linear. In many shrubby species the leaves are concentrated on short lateral shoots, giving the plant a distinctive tufted look. A useful field habit is to look at the underside of a leaf: the felted, silvery or rusty hairs found there in many species are a strong clue.

### Habit and habitat

Most wild buckwheats grow in full sun on well-drained ground: sand, gravel, volcanic soils, rocky slopes, road cuts and desert flats. They are rarely found in shade or in wet, heavy soil. A plant with tiny dense flower heads, a cup-like involucre, woolly leaves and a position on a dry, open slope is a strong candidate for Eriogonum.

Which buckwheat should a small dry garden start with?

### Sulfur buckwheat (Eriogonum umbellatum)

Sulfur buckwheat is a low, mat-forming to mounding subshrub with yellow flowers that age to orange or rust. It is widespread across the western United States, which means a local seed source is usually available, and it tolerates a range of soils as long as drainage is sharp. It is a reasonable first plant for a rock garden or a dry border.

### California buckwheat (Eriogonum fasciculatum)

California buckwheat is a shrubby species, often a metre or more tall, with small white to pinkish flower heads that turn rust-brown in autumn. It is a workhorse of low-water gardens in California and the Southwest, and it is one of the most reliable late-summer nectar plants for bees and butterflies. It wants full sun and no summer water once established.

### Saint Catherine's lace (Eriogonum giganteum)

Saint Catherine's lace is the large one: a shrub that can reach two metres or more, with broad grey-white flower heads. It is native to the Channel Islands and coastal southern California, and it is best suited to a garden with room for a substantial plant and a frost-free or nearly frost-free site.

### What to do in the first season

Plant in autumn, not spring, so the roots have cool, wet months to establish before the first dry summer. Water sparingly through the first summer, then taper off. Do not enrich the soil: these plants evolved on poor ground, and fertility encourages soft growth that will not survive a dry season. A gravel mulch keeps the crown dry and the leaves clean. Light pruning after flowering keeps shrubs compact, and it is best done in late winter or immediately after seed set, never hard into old wood.

Why the genus matters beyond the garden

Wild buckwheats are late-summer nectar plants, and that timing is their ecological importance. When many western wildflowers have finished, Eriogonum is still flowering, and the bees, butterflies and hummingbirds that depend on that late resource are tied to it. A dry garden planted with buckwheat is not only a low-water planting; it is a seasonal food source.

The genus also has a documentary history. The botanist James L. Reveal spent much of his career mapping Eriogonum, and his treatments remain the standard reference for the group. The Eriogonum Society, now publishing at eriogonum.community, is described in the third person by the journal, as are the nurseries and societies it mentions. The journal sells nothing and belongs to no nursery and no society.