1. Valerianella Mill. (corn salad, lamb’s lettuce)

Plants annual or less commonly biennial. Stems usually dichotomously forked several times, angled, glabrous or sparsely and inconspicuously hairy along the angles. Basal leaves sessile or short-petiolate, the blades simple, spatulate to obovate, mostly rounded at the tip, the margins mostly entire, grading into the stem leaves; stem leaves mostly sessile, often with the bases fused around the stem, oblong-spatulate to lanceolate, rounded to bluntly pointed at the tip, the margins entire or few-toothed near the base, glabrous or more commonly inconspicuously hairy along the margins and the midvein of the undersurface. Stipules absent. Inflorescences dense small headlike clusters, these solitary or more commonly paired at the branch tips, with small lanceolate to narrowly elliptic or narrowly spatulate bracts surrounding each cluster. Flowers mostly perfect, epigynous, each subtended by a small bractlet. Calyces absent or reduced to a minute crown. Corollas actinomorphic or slightly zygomorphic, 5-lobed, trumpet-shaped to narrowly bell-shaped, the tube often inconspicuously pouched at the base. Stamens 3, the filaments attached near the top of the corolla tube, the anthers attached at their midpoint, white. Pistils 1 per flower, apparently of 3 carpels. Ovary inferior, with 3 locules, but only 1 of these fertile, with 1 ovule, the others empty. Style 1, the stigma usually slightly 3-lobed. Fruits achenelike, usually straw-colored at maturity, the fertile locule becoming leathery and indehiscent, the sterile locules persistent and differentiated in shape and size from the fertile one. About 60 species, North America, Europe, Asia.

Species of Valerianella are classified principally on the basis of fruit morphology, thus some specimens lacking fruits can be difficult to determine with confidence. However, crossing experiments have shown that distinctive fruit morphologies within some species complexes are actually the result of minor genetic variations (see below for more discussion). The vernacular names “corn salad” and “lamb’s lettuce” refer to the use of young plants of several species in the genus as potherbs and salad greens.