Annual herb to 0.5 m tall Stem: erect. Leaves: opposite, stalkless, spoon-shaped near base, lance-shaped near tip. Flowers: borne terminally in a small compact cluster (glomerule), subtended by hairless bracts, 3 - 5 mm across, with minute or absent sepals, white petals fused into a five-lobed tube, and three stamens. Fruit: dry, 2 - 5 mm across, nearly circular in cross-section, three-chambered with one chamber fertile and one-seeded and the other chambers empty but sometimes inflated. The fertile chamber is egg-shaped and usually narrower than both sterile chambers combined.
Similar species: Valerianella species have non- or few-toothed stem leaves and tiny or absent calyx lobes. Valerianella locusta is distinguished by its fruit with a corky mass on the back of the fertile chamber. Valerianella umbilicata differs by having fruit that is triangular in cross-section and has a fertile chamber that is much wider than the other two chambers combined.
Flowering: mid May to early July
Habitat and ecology: Low woods and wet soil, generally rare in our region but common on Langham Island in the Kankakee River and occasional on the river shore at Kankakee River State Park.
Occurence in the Chicago region: native
Etymology: Valerianella is a diminutive of Valeriana, referring to the similarity between the two genera. Umbilicata means navel-shaped.
Infl loosely fld, with elongate branches; cor white, 3-5 mm; its lobes 1-2 mm; fr trimorphic, 3-5 mm, 2 forms near orbicular in dorsal (abaxial) view, the fertile locule ovoid, the sterile ones much dilated, their lateral walls relatively firm, ±incurved on the adaxial side, the ventral walls very thin and membranous, soon ruptured to expose a deep and narrow or shallow and broad adaxial pit; in the third type the sterile locules not expanded, together forming an ovoid, medially grooved protuberance hidden from abaxial view by the fertile locule. Local from s. N.Y. and s. Ont. to Ill., s. to N.C. and Tenn. May, June. (V. intermedia; V. patellaria)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.