1. Atriplex L. (saltbush, orach, orache)

Plants annual, monoecious (dioecious perennial herbs or shrubs elsewhere), the roots not tuberous-thickened. Stems prostrate to erect, sometimes weak and supported by surrounding plants, not succulent, not appearing jointed, usually much-branched, glabrous or sparsely to moderately mealy, at least when young. Leaves alternate or opposite toward the stem base, well developed, not or only slightly succulent, mostly petiolate. Leaf blades narrowly lanceolate to ovate or triangular, often with a pair of pronounced, spreading basal lobes, flattened in cross-section, not clasping the stem, rounded or narrowed to a sharply pointed tip, the margins entire or sometimes slightly wavy, the surfaces glabrous or sparsely to densely mealy. Inflorescences axillary and/or terminal, consisting of small flower clusters (sometimes solitary flowers), these often appearing as interrupted spikes, or small panicles of interrupted spikes, the staminate flowers intermingled with the pistillate flowers or positioned more terminally along the inflorescence, the flowers not sunken into the axis. Bracts of staminate flowers absent (or sometimes minute bracts subtending flower clusters); bracts of pistillate flowers 2, longer than the flower (absent in some flowers of dimorphic species), more or less fused basally, enclosing the fruit, broadly triangular to rhombic or nearly circular, sometimes strongly veined or ornamented with flaplike or hornlike projections, the margins entire or toothed. Calyx absent in pistillate flowers (present sometimes in dimorphic species, then similar to that of staminate flowers), calyx in staminate flowers 1.5–2.5 mm long, deeply (3–)5-lobed, the lobes spaced evenly around the flower, the tips erect or incurved. Staminate flowers with (3–)5 stamens. Pistillate flowers with the ovary superior. Styles 2, short, sometimes fused at the very base, the stigmas 1 per style, linear. Fruits broadly obovate to nearly circular in outline, somewhat flattened laterally, usually indehiscent, the wall thin and papery to membranous. Seed adhering loosely to the fruit wall, usually positioned vertically, sometimes dimorphic, somewhat flattened, the surface smooth, brown or black, shiny, the coiled embryo usually apparent. About 300 species, nearly worldwide.

Some shrubby species of Atriplex (saltbushes) are major components of scrubby vegetation types in the arid portions of the western United States. Nearly all of the species are adapted to grow well in saline soils. The eastern species are annuals of disturbed habitats and for the most part are closely related components of a circumboreal polyploid complex. Species determinations among the taxa present in Missouri are difficult, and mature fruits are usually necessary for certain identification.