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..
Annual erect herbs, half parasitic on the roots of other plants, with small opposite leaves, and yellow or red flowers in terminal bracted spikes or racemes. Calyx 4-toothed. Corolla with a narrow tube and a strongly 2-lipped limb, the upper lip concave, entire, or 2-lobed, the lower 3-lobed, spreading. Stamens 4, didynamous, ascending; anther-sacs similar. Capsule mostly subglobose, loculicidally dehiscent. Seeds few, pendulous. [Greek, referring to its supposed value as a cure for toothache.]
About 20 species, mostly natives of the Mediterranean region, the following typical.
Annual, appressed-pubescent, roughish; stem slender, at length much branched, 6'-15' high, the branches erect or ascending. Leaves sessile, lanceolate, or oblong-lanceolate, acute or acuminate at the apex, serrate with low distant teeth, slightly narrowed at the base, 1/2'-1 1/2' long, 1"-3" wide; spikes slender, becoming 2'-5' long in fruit, somewhat 1-sided; bracts similar to the leaves, but smaller; flowers numerous, 4"-5" long; calyx 4-cleft; corolla red or pink, its tube somewhat longer than the calyx; anthers slightly pubescent; capsule oblong, shorter than the calyx.
In fields and waste places, coast of Maine to Nova Scotia. Naturalized from Europe. Native also of Asia. June-Sept.