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..
An annual erect finely viscid-pubescent much-branched herb, with narrow entire or few-toothed leaves, and small blue flowers in loose axillary cymes. Calyx broadly campanulate, 10 - nerved, nearly equally 5-toothed, the teeth lanceolate. Corolla-tube not longer than the calyx, enlarged into the throat, the limb nearly equally 5-cleft into obovate somewhat spreading lobes. Stamens 4, didynamous, incurved-ascending, not longer than the corolla, the anterior pair slightly the longer; anther-sacs divergent at maturity. Ovary deeply 4- lobed; style minutely 2-cleft at the summit. Nutlets rugose-reticulated. [Greek, equal-flower, the corolla-lobes being nearly equal.] A monotypic genus of eastern North America.
Trichostema brachiatum L. Sp. Pl. 598. 1753. tsanthus coeruleus Michx. Fl. Bor. Am. 2: 4.
pl. 30. 1803. 1. brachiatus B.S.P. Prel. Cat. N. Y. 44. 1888.
Stem slender, much branched, 6'-2o' tall, the branches spreading. Leaves oblong or elliptic-lanceolate, acute at each end, entire, or with a few sharp teeth, 3-nerved, short-petioled, 1-2' long, 2"-6" wide; axillary cymes 1-3-flowered; pedicels very slender, some of them as long as the fruiting calyx; calyx-lobes acute or acuminate, longer than or equalling the tube; corolla 2"-3" long, the fruiting calyx 3" long.
In sandy soil, especially along streams, Quebec and Ontario to Minnesota, Vermont, Georgia, Kansas and Texas. Flux-weed. Blue gentian. July-Sept.