Annual or perennial herb 40 cm - 1.5 m tall Stem: erect, branching near base, nearly hairless to minutely stiff-haired. Leaves: opposite, stalked, 5 - 20 cm long, more than 2 cm wide, egg-shaped and tapering to a pointed tip, coarsely toothed, nearly hairless to densely velvet-haired beneath. Inflorescence: a branched cluster of numerous spikes, each ascending spike less than 7 mm thick, with flowers well separated along the spike. Flowers: white, subtended by 0.5 - 1.5 mm long bracts that are egg-shaped with pointed tips and hairy along the margin. The calyx is 2 - 2.3 mm long, triangular-lobed, and hairy, and the corolla is barely longer than the calyx and has blunt lobes. Fruit: four nutlets surrounded by the persistent calyx but exposed at the top, each nutlet 1 - 2 mm long with a smooth and flat or wrinkled back.
Similar species: Verbena urticifolia and Verbena hastata have more than three flower spikes per cluster. Verbena hastata differs by its lance-shaped to narrow egg-shaped leaves and its bluish purple flowers that overlap along the spike. Verbena urticifolia is represented by two varieties in the Chicago Region. See links below for further information.
Etymology: Verbena is the Latin name for vervain. Urticifolia means nettle-leaved.
Erect, single-stemmed annual or perennial, 4-15 dm, often branching from near the base; lvs broadly lanceolate to oblong-ovate, petiolate, 5-12 cm, coarsely and somewhat doubly crenate-serrate; spikes paniculately disposed, slender; bracts ovate, acuminate, ciliate; cal-teeth short, subequal; cor white, the tube scarcely exserted, the limb 2(-4) mm wide, the lobes obtuse; fr exposed at the top; nutlets
1-2 mm; 2n=14. Thickets, moist fields, meadows, and waste places; N.B. (?) and Que. to N.D., s. to Fla. and
Tex. June-Oct. Var. urticifolia, with the range of the sp., has the lvs hirtellous or glabrous on both sides, the
hairs whitish, 1-1.3 mm, the cal strigose, 2-2.3 mm at maturity, and the nutlets 2 mm, corrugated on the back.
Var. leiocarpa L. M. Perry & Fernald, with more restricted range, from Conn. and Pa. to N.D., S.C., and Okla., has the lvs densely velutinous with hairs to 0.3 mm, the mature cal puberulent, to 2 mm, the nutlets 1.5 mm, smooth. A hybrid with V. stricta is V. ةllicita Moldenke; one with V. hastata is V. إngelmannii Moldenke.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.