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 or biennial, somewhat hirsute, simple or little branched herb, with longpetioled ovate cordate crenate leaves, and large whitish flowers in a terminal leafy-bracted spike. Calyx campanulate-oblong, membranous, deeply 4-cleft, inflated in fruit, faintly and irregularly veined, the lobes narrowly lanceolate, the two upper shorter than the lower.
Corolla much longer than the calyx, its tube narrow below, much expanded above, 2-lipped; upper lip concave, entire; lower lip spreading, 3-lobed. Stamens 4, didynamous, ascending under the upper lip of the corolla; filaments villous; anthers glabrous, 2-celled, the sacs divaricate, the contiguous ones of the upper pair of stamens sterile and connate. Ovary deeply 4- lobed; style unequally 2-cleft at the summit. Nutlets ovoid, smooth, sharply angled.
A monotypic genus of southeastern North America.
Lamium hispidulum Michx. Fl. Bor. Am. 2: 4. 1803. Synandra grandiflora Nutt. Gen. 2: 29. 1818. Torreya grandiflora Raf. Am. Month. Mag. 3: 356. 1818. S.. hispidula Britton, Mem. Torr. Club 5: 285. 1894.
Stem rather slender, erect or ascending, weak, 1°-2 1/2° long, striate. Leaves thin, the lower and basal ones broadly ovate, or nearly orbicular, pal-mately veined, acute or obtuse at the apex, deeply cordate at the base, the blade 2-4' long, and commonly shorter than the petiole; floral leaves sessile, ovate or ovate-lanceolate, acute or acuminate, the flowers solitary in their axils, the uppermost leaves very small; calyx hirsute, its lobes about as long as the tube; corolla 1'-1 1/2' long, showy, the lower lip with purple lines.