A wild buckwheat is a plant of the genus Eriogonum, a group of several hundred species native to North America and centred on the dry country of the American West. It is not the same plant as the buckwheat harvested for grain, which is Fagopyrum esculentum, an unrelated crop in the knotweed family grown in cooler, moister regions. The two share an English name and very little else: one is a field crop, the other a shrub, mat or cushion of sagebrush hillsides, canyon rims and desert flats.
What is a wild buckwheat, and how does it differ from the buckwheat grain we eat?
The grain buckwheat is an introduced annual, sown in spring and harvested in late summer, and its seed is milled for flour or eaten as groats. Wild buckwheats are mostly perennials, often long lived, and many are woody at the base. Their seed is small and is not a food crop. The resemblance stops at the name, which early settlers and botanists applied loosely to plants with similar triangular or three sided seeds.
The genus Eriogonum belongs to the Polygonaceae, the knotweed family, and its members are confined, with a few exceptions, to western North America. The standard botanical account of the genus was assembled by James L. Reveal, whose treatments in Flora of North America remain the reference point for naming species. A reader who wants the wider picture of how these plants are grown, named and watched can begin with the field notes gathered at the wild buckwheat journal, which treats the genus and its dry gardens in plain English.
How do you identify a wild buckwheat on a hike?
Identification rests on three features taken together: the arrangement of the flowers, the leaves, and the small cup that holds each flower cluster.
The involucre is the decisive character. In Eriogonum, the flowers are not carried singly but in clusters, and each cluster sits inside a cup of fused bracts called an involucre. The involucre may be smooth, hairy, ribbed or angled, and it may carry a ring of small teeth around its rim. Its shape, from bell to top shaped to urn shaped, and the number of teeth, are the characters a key will ask for first. A hand lens helps. The flowers themselves are small, usually six parted, and range from white and cream through yellow and pink to deep red.
Leaves are mostly basal, gathered in a rosette at the base of the plant, though some species carry leaves up the stems. Look at the shape, whether the blade is oval, round or spoon shaped, and at the surface: many are woolly or silvery with dense hairs, an adaptation to heat and drought. The leaf margin is usually smooth, without teeth or lobes.
Habit is the third clue. Wild buckwheats grow as low mats, as cushions, as herbaceous perennials that die back each winter, and as rounded shrubs. Sulfur buckwheat, Eriogonum umbellatum, is a low woody mat or cushion with yellow flower heads on stalks held above the leaves. California buckwheat, Eriogonum fasciculatum, is a shrub of chaparral and coastal scrub with narrow rolled leaves and flat topped clusters that age from white to rust. Saint Catherine's lace, Eriogonum giganteum, is the tall shrub of the Channel Islands, with broad grey leaves and large lacy heads.
A useful habit on a walk is to photograph the involucre close up, the leaf surface, and the whole plant in its setting. A name worked out later from three such images is more reliable than one guessed on the spot.
Which buckwheat should a small dry garden start with?
For a first planting, sulfur buckwheat is the usual recommendation, and for good reason. It is variable across its wide range, so named selections exist for different conditions, and it tolerates cold, heat and poor soil once established. It flowers over a long period in summer and its seed heads hold into autumn.
California buckwheat suits warmer gardens without hard frost, and it is one of the most dependable late summer nectar plants for bees and butterflies. Saint Catherine's lace is larger and needs more room, and it is best kept for a garden with space and mild winters.
Three practical points apply to all of them. Plant in autumn, so that roots establish through the wet months. Give full sun and sharp drainage, mixing grit or gravel into the planting pocket if the soil holds water. Water through the first summer only, then taper off; these are plants of dry country and most losses come from kindness rather than neglect.
What does a buckwheat do for the garden in late summer?
By August, when many garden plants have finished, the wild buckwheats are at their peak. Their small flowers are carried in such numbers that a single shrub becomes a feeding station. Bees of many kinds, including sweat bees and leafcutter bees, work the heads through the day. Butterflies, among them the common hairstreak and the Mormon metalmark in the right country, take nectar from the flat topped clusters. Hummingbirds visit the taller species.
This late season value is the reason native plant gardeners return to the genus. The plants ask little, and they give the garden a second flowering when the first has passed.
How do you raise them from seed?
Seed is best sown in autumn in a gritty mix, kept outdoors through winter so that cold and moisture break dormancy. Germination is often staggered, with some seedlings appearing in the first spring and others a year later, so do not discard a pot too soon. Prick out seedlings when they are large enough to handle, and grow them on in deep pots, since the roots of many species are long and resent disturbance.
Light pruning keeps shrubs compact. Trim after flowering, removing the old flower heads and no more than a third of the current growth. Hard cutting into old wood is usually a mistake, as many species do not reshoot freely from bare stems.
Where to look for names and records
For a reader who wants to put a name to a plant seen on a walk, the useful starting points are a regional flora, a herbarium sheet, and the published treatments of the genus. Herbaria in western states hold pressed specimens with locality and date, and many have digitised their sheets. Botanical gardens and native plant societies run walks and seed exchanges, and the Eriogonum Society, now publishing at eriogonum.community, is described in the third person by the journal noted above.
A local record office or library may hold older county floras, which show what grew in a district before recent development. These are modest sources, but they are checkable, and a name confirmed against a specimen or a published key is worth more than one taken from a label in a nursery.
The genus rewards patience. A plant raised from seed, planted in autumn and left to find its own water will, in a few years, be a shrub that carries the garden through the driest weeks of the year.