Systematic and Geographical State of Atriplex

Abstract

There are several important reasons for undertaking a serious, but limited review of the systematics of the genus Atriplex. First, many of the species which have attracted ecological and physiological attention in the past are members of large species complexes. Some of these complexes have been examined recently, species have been renamed, regrouped, and sometimes subdivided. We have attempted to translate the species name used in original ecological and physiological reports into the currently accepted species name throughout the book. Second, a reasonably accurate estimate of the number of species is an essential starting point for a discussion of geographical distribution and of the generic processes of evolution and radiation of these plants. Third, because the systematics of the genus is largely based on differences in morphological characters, some of which are functional and significant in physiological and ecological processes, a review of systematics and geography may indicate trends or relationships which are helpful in evaluating these processes. With an agreed and reasonably accurate species list it may even be possible to present these trends or relationships in quantitative terms.

“Annual and perennial herbs and shrubs, more or less pubescent with inflated scurf-like hairs. Leaves alternate, or the lower opposite, rarely all opposite, sessile or petioled, entire to dentate or irregularly and deeply lobed. Flowers monoecious or dioecious, solitary or in glomerules, the single or clustered flowers in the leaf-axils and often also in terminal spikes or panicles, the staminate and pistillate flowers often mixing in the same cluster, but the staminate usually confined to the upper axils or to terminal inflorescences. Staminate flowers without bracts or bracteoles; perianth 3- to 5-parted, the segments obovate or oblong and obtuse; stamens 3 to 5, inserted on the base of the perianth, the filaments either united at the base or distinct, the anthers 2-celled; rudiment of the ovary conical or wanting. Pistillate flowers each subtended by 2 bracts; bracts accrescent, distinct or usually united at least at the base and inclosing the fruit, entire or the margins variously dentate, sometimes fleshy-thickened or spongious; perianth none or rarely present and then consisting of a 3- to 5-lobed membranous calyx or of 1 to 5 squamellae; disk and rudimentary stamens wanting; ovary ovoid or depressed-globose; stigmas 2, nearly filiform, or slightly thickened or compressed near the base, where also shortly connate; ovule oblique or erect and with a short funicle, or inverted and suspended from the end of an elongated funicle. Utricle inclosed between the bracts, the pericarp membranaceous and usually free from the seed. Seed erect or inverted, rarely horizontal, the coats membranaceous, coriaceous or almost crustaceous; embryo annular, surrounding the farinaceous albumen, the radicle inferior, lateral, or superior”. (Hall and Clements, 1923)

“It’s the damnest stinking genus there is, taxonomically” (M. Nobs, pers. comm.)