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..
A perennial erect finely pubescent and minutely glandular, simple or sparingly branched, leafy herb, with sessile entire 3-nerved leaves, and rather large yellowish-purple flowers in a terminal bracted spike. Calyx tubular, somewhat oblique, 10-12-ribbed, 2-bracteolate at the base, 5-toothed, the upper tooth much the smallest, the 2 lower ones partly connate; corolla very irregular, the tube cylindric, the limb 2-lipped; upper lip arched, concave, entire; lower lip somewhat shorter, 3-lobed, 2-plaited. Stamens 4, didynamous, ascending within the upper lip of the corolla; anther-sacs equal. Style filiform. Capsule oblong, many-seeded. Seeds linear, with a loose reticulated testa. [Named for C. G. Schwalbe, of Holland, who wrote (1719) on Farther India.]
A monotypic genus of eastern North America.
Schwalbea americana L. Sp. Pl. 606. 1753- Stem slender, strict, 1°-2° high. Leaves oblong or ovate-oblong, entire, acute at both ends, l'-l 1/2' long, 2"-8" wide, the upper gradually smaller and passing into the bracts of the rather loose spike; flowers very nearly sessile, 1'-1 1/2' long, longer than the bracts; bractlets at the base of the calyx linear, shorter than its tube; corolla-tube slightly exceeding the lower lobes of the calyx, these connate to near their apices; capsule enclosed by the calyx.
In wet sandy soil, eastern Massachusetts to Florida and Louisiana, near the coast. May-July.