This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Annual or perennial. Propagates by seeds. Time of bloom: May to July. Seed-time: June to August. Range: Minnesota to British Columbia, southward to Georgia, Florida, Texas, and California. Habitat: Plains and prairies; grasslands, waste places.
Stems numerously branched from the base, some prostrate and some ascending, very slender, four-sided, rough-hairy, six to fifteen inches long. Leaves broadly wedge-shaped in outline but pinnatifid, the lobes cut and toothed, the basal pair spreading and narrowing abruptly to short, margined petioles. Spikes single, the blossoms being scattered somewhat remotely along each spike and having the hairy bracts subtending the flowers very long and stiff, the lower ones pinnatifid, nearly concealing the small, purplish blue corollas. Each plant produces many of the little nutlets which foul the soil worse than other species because of their earlier maturity. Seed-bearing plants are often transported in baled hay, and the weed has of recent years been thus introduced in a number of widely separated localities in the northeastern part of the country.
Means of control the same as for V. stricta.
Fig. 238. - Blue Vervain (Verbena hastata).