Shrubs Of The Great Basin: A Natural History

Kearney's Buckwheat

Kearney's Buckwheat Eriogonum keameyi ALMOST AS characteristic of the Great Basin as shadscale and sagebrush are the various species of wild buckwheat. Some of the latter are annual or perennial herbaceous plants, but many are woody, at least at the base. Some authorities call them subshrubs. If we were to discuss all these partially woody forms, we would have to consider perhaps thirty-five species within the Great Basin. Fortunately, most of these are low, compact forms that, to the uninitiated, appear to be wildflowers rather than shrubs. Separating many of these into species is a job best left to the expert. Consequently, in this book we shall confine our discussions to those wild buckwheats which are pretty obviously shrubs, and save the others for the wildflower book in this series. Kearney's buckwheat is one of the tallest in the genus. It frequently attains a height ofover I meter. Outside of the Basin in southern Nevada, the California buckwheat, E. fasciculatum, not uncommonly gets to be 2 meters and sometimes 3 meters tall. Confined primarily to sandy areas, Kearney's buckwheat is a conspicuously large and diffusely branched shrub. In areas with sand dunes, clumps may be several meters in diameter on the tops of small dunes. Obviously, they assist to some extent in stabilizing dune areas, though they are not as important as certain other dune plants. The pubescent, I-to-3-centimeter leaves are sparsely scattered along the lower stems, which are also pubescent. The upper part of the stem tapers to a many-branched inflorescence which bears numerous small, whitish flowers. Examination of these flowers under a hand lens will reveal the pattern characteristic of all the buckwheats: two whorls, consisting of three whitish sepals each, enclosing nine stamens (sometimes fewer) and a single Kearney's Buckwheat 94 POLYGON ACEAE pistil in the center. There are no petals and, even though the sepals are colored like petals in the buckwheats, they are structurally not petals. Long ago in the evolution of the buckwheats, the petals, for some reason, were lost. And, as we have seen elsewhere, "nature" changed its mind, decided that petals were needed once again, and formed them from sepals. Of course, nature doesn't have a mind to change; this is but one more example of the randomness of evolution. It also illustrates the fact that, once the genes for a particular structure have been lost, they can't be resurrected. The best that can be done is to take the genes for another structure, in this case the sepals, and change them to produce something that resembles the lost petals. But, ofcourse, this is all the result ofnatural selection and the appro~ priate hereditary variations-it is not a purposeful evolution of these struc~ tures on the part of the plant. The pistil in the wild buckwheats matures into a triangular fruit called an achene. Except for its much smaller size, its appearance is very much like that of the cultivated buckwheat achene. The family to which the wild and cultivated buckwheats belong is the Polygonaceae. There are around thirty genera and over a thousand species in this largely temperate~zone family. Incidentally, although most members of the family have the flower parts in threes, as do the buckwheats, the fam~ ily does not belong to that major group of flowering plants called the mono~ cots. Virtually all beginning botany texts recite the litany that flower parts are in threes in the monocots and in fives in the dicots. But, as with most such generalizations, there are always exceptions. In fact, a few members of the buckwheat family do have five petallike sepals (but no true petals). In~ terestingly enough, these five~part flowers have evolved from the usual two whorls of three sepals by a fusion ofone member of the inner whorl with one member of the outer whorl. Threes and fives seem to be magic numbers in the flowering plants! The genus name Eriogonum comes from two Greek words, erion which means wool and gonu which means knee. Many of the buckwheats have a woolly pubescence, and, like other members of the same family, one of their distinctive features is a stem node which is characteristically swollen and sometimes bent. In some Eriogonums these nodes are especially hairy, ac~ KEARNEY'S BUCKWHEAT 95 counting for the genus name. The genus consists ofperhaps 150 species con~ fined to...