This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Perennial, densely soft-pubescent all over with whitish hairs; stem stout, obtusely 4-an-gled, simple, or branched above, strict, very leafy, 1°-2 1/2° high. Leaves ovate, oval, or oblong, very short-petioled, acute or obtuse at the apex, narrowed at the base, prominently veined, incised-serrate or laciniate, 1'- 4' long; spikes solitary, or several, mostly sessile, dense, stout, becoming 6'-12' long in fruit; fruits much imbricated, 2"-2 1/2" high; bracts lanceolate-subulate, nearly as long as the calyx; corolla purplish blue, 4"-5" long, its limb nearly as broad.
In dry soil, Ontario and Ohio to Minnesota, South Dakota and Wyoming, south to Tennessee, Texas and New Mexico. Naturalized as a weed further east. Hybridizes with V. bracteosa. June-Sept.
V. bracteosa Michx. Fl. Bor. Am. 2: 13. 1803.
Perennial, hirsute-pubescent; stem 4-sided, much branched from the base, the branches decumbent or ascending, slender, 6'-15' long. Leaves ovate, oval, or obovate in outline, pin-nately incised or pinnatifid, 1'- 3' long, more or less cuneate at the base and narrowed into short petioles, the lobes mostly dentate; spikes sessile, stout, dense, becoming 4'-6' long in fruit; bracts conspicuous, linear-lanceolate, rather rigid, longer than the flowers and fruits, the lower ones often incised; corolla purplish blue, about 2" long.
On prairies and in waste places, Minnesota and Illinois to Virginia, Alabama and Florida, west to British Columbia, Arizona and California. In ballast grounds at Atlantic seaports. Hybridizes with V. canadensis. Prostrate vervain. May-Aug.
Buchnera canadensis L. Mant. 88. 1767.
1796. Verbena canadensis Britton, Mem. Torr. Club 5: 276. 1894.
Perennial, pubescent or glabrate; stem slender, usually branched, 8'-20' high, the branches ascending. Leaves membranous, ovate in outline, petioled, 1'-3' long, truncate or broadly cuneate at the base, irregularly toothed, or pinnately incised, often 3-cleft, the lobes dentate; spikes peduncled, solitary at the ends of the branches, dense, short and capitate when in early flower, becoming 2'-4' long in fruit; bracts linear-subulate, mostly shorter than the calyx; calyx-teeth filiform-subulate; corolla 10' -12" long, blue, purple, white or in cultivation variegated, its limb 7"-12" broad, the lobes oblong or obovate, emargi-nate or obcordate; fruit 2 1/2"- 3" high.
In dry soil, Illinois to Tennessee, Virginia and Florida, west to Kansas and Texas. This and the next the source of many garden and other hybrids. Cut-leaved races have been referred to V. Drummondii (Lindl.) Baxter. May-Aug.
Soc. (II.) 5: 184. 1833-37. Verbena ambrosiaefolia Rydb.; Small, Fl. SE.
U. S. 1011. 1903.
Perennial, producing suckers, hirsute or hispid; stems rather stout, mostly branched, erect, 6'-18' high. Leaves firm, petioled or the uppermost sessile, broadly ovate in outline, deeply 1-2-pinnatifid into linear or linear-oblong, obtuse or subacute lobes and segments; spikes peduncled or sessile, solitary at the ends of the branches, thick, dense, at first short and capitate, becoming 2-4' long in fruit; bracts linear-subulate, about as long as or somewhat exceeding the calyx; calyx-teeth filiform-subulate; corolla 6"-9" long, purple or lilac, the limb 4"-7" broad, the lobes emarginate or obcordate; fruit 1 1/2"- 2" long.
On dry plains and prairies, South Dakota to Missouri, Texas and Chihuahua, west to Colorado and Arizona. May-Sept.