V. officinàlis, L. (European V.) Annual, glabrous or nearly so, loosely branched (1–3° high); leaves pinnatifid or 3-cleft, oblong-lanceolate, sessile, smooth above, the lobes cut and toothed; spikes panicled; flowers purplish, very small.—Roadsides and old fields, N. J. to Minn., south to Tex., and westward. (Nat. from Eu.)
1. V. urticæfòlia, L. (White V.) Perennial, from minutely pubescent to almost glabrous, rather tall (3–5° high); leaves oval or oblong-ovate, acute, coarsely serrate, petioled; spikes at length much elongated, loosely panicled; flowers very small, white.—Waste or open grounds. (Trop. Am.)
[*][*] Spikes thicker or densely flowered; the fruits crowded, mostly overlapping each other; bracts inconspicuous, not exceeding the flowers; perennial.
2. V. angustifòlia, Michx. Low (6–18´ high), often simple; leaves narrowly lanceolate, tapering to the base, sessile, roughish, slightly toothed; spikes few or single; the purple flowers crowded, larger than in the next.—Dry or sandy ground, Mass. to Minn., south to Fla. and Ark.
3. V. hastàta, L. (Blue Vervain.) Tall (4–6° high); leaves lanceolate or oblong-lanceolate, taper-pointed, cut-serrate, petioled, the lower often lobed and sometimes halberd-shaped at base; spikes linear, erect, corymbed or panicled; flowers blue.—Waste grounds and roadsides; common.
4. V. strícta, Vent. (Hoary V.) Downy with soft whitish hairs, erect, simple or branched (1–2° high); leaves sessile, obovate or oblong, serrate; spikes thick, somewhat clustered, hairy; flowers rather large, purple.—Barrens and prairies, Ohio to Dak., south to Tex. and N. Mex.
[*][*][*] Spikes thick, sessile and leafy-bracted; annual.
5. V. bracteòsa, Michx. Widely spreading or procumbent, hairy; leaves wedge-lanceolate, cut-pinnatifid or 3-cleft, short-petioled; spikes single, remotely flowered; bracts large, the lower pinnatifid, longer than the small purple flowers.—Prairies and waste grounds, Ohio to Minn., south and westward.
§ 2. Anthers of the longer stamens glandular-tipped; flowers showy, from depressed-capitate becoming spicate.
6. V. bipinnatífida, Nutt. Hispid-hirsute, ½–1° high; leaves (1½–4´ long) bipinnately parted, or 3-parted into more or less bipinnatifid divisions, the lobes commonly linear or broader; bracts mostly surpassing the calyx; limb of bluish-purple or lilac corolla 4–5´´ broad.—Plains and prairies, Kan. to Ark. and Tex., and westward.