Shrubs Of The Great Basin: A Natural History

Desert Blite

Desert Blite Suaeda torreyana THE DESERT PLAYAS of the Great Basin are in many ways as hostile to higher plant life as the bleakest Antarctic landscape. Frequently there grows a thin stand of scraggly shrubs at the edge of and partly onto the larger playas. On examination, this almost always turns out to be the desert blite, S. torreyana. Neither heat nor lack of water is the barrier to colonization in such areas by higher plants. It is, rather, the extremely high salt content of the soil that, in many instances, totally inhibits the growth of all higher plants. Some halophytic bacteria and algae have solved this physiological problem, but mosses, ferns, and all higher plants are totally absent from the most saline locations. Because of the tremendous plasticity of living forms on this earth, it is tempting to believe that, provided it is not too hot or too cold, living things can eventually adapt to any habitat. This is a generalization which, if re, stricted to the most primitive forms, holds well enough. But apparently there has not been enough time since seed plants first evolved, some 300 million years ago, for them to solve this particular problem. Some flowering plants have gotten back into salt water, notably such forms as the eel grass and turtle grass that thrive on the continental shelf. But they have very few competitors among higher plants-only several among the hundreds of higher plant families have been able to make the transition to salt water. In the case of desert playas, the salt concentration is frequently much higher than that of the oceans, and the situation is additionally complicated by the lack of water at some time during the year. We now think that some of the difficulty lies with the poisonous nature of sodium in such soils, at least for certain plants. Plants such as the shadscale, tamarisk, and eel grass that can resist relatively high salt concentrations are Desert Blite, winter aspect DESERT B LITE apparently able to do so as a result of a cellular mechanism that accumulates and excretes salt. This excretion requires a good deal of cellular energy as well as a complicated structure, which most plant families have not evolved. However, some salt~tolerant plants, such as the desert blite, are not able to excrete salt but simply continue to accumulate it in their leaves during the growing season. When the leaves die and are shed at the end of the season, the accumulated salt is also shed. Year after year of this sort of thing results in the surface layers of the soil having a much higher salt concentration, to the extent that few other plants are able to get started as seedlings. The ferns, which have been here at least 100 million years longer than the seed plants, have never managed to evolve a salt tolerance. And there are no saltwater mosses. Since the earth is destined, according to some, to become drier and more saline, our desert shrubs, with their adaptations to this extreme environment, may give us a glimpse into the future possibilities for evolution in higher plants. The goosefoot family, to which the desert blite belongs, is certainly the most successful land plant family in solving the twin problems of aridity and salinity; it may well be the model for future flowering plants on the earth! Desert blite varies in height from 30 centimeters to I meter. Its branches are only sparsely leafy, at best, with flat, narrow leaves about 2 millimeters wide and 30 millimeters long. The flowers are very small, greenish, and in~ conspicuous, being only 2 to 3 millimeters broad. The five~lobed calyx en~ closes the fruit at maturity. There are no petals, five stamens (sometimes fewer), and one pistil containing a single seed. If the flowers are closely ex~ amined, some will be seen to lack stamens while others lack pistils, even though most of the flowers will have both. A variable pattern such as this can be regarded as the first step on the road to a species with the sexes com~ pletely separated on different plants, as is true of many other members of the goosefoot family. Desert blite, as well as other related species, was utilized by the Indians to prepare a tea which they believed was useful for kidney problems. Ad~ ditionally, it was thought that the juice from the plant...