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..
Herbs, with dentate entire or incised leaves, and blue or purple flowers in axillary and terminal bracted clusters, the bracts pectinate in our species. Calyx tubular, 15-nerved, straight or incurved, 5-toothed, the upper tooth much larger than the others, or 2-lipped with the 3 upper teeth more or less united. Corolla expanded above, its limb 2-lipped; upper lip erect, emarginate; lower lip spreading, 3- lobed, the middle lobe larger than the lateral ones, sometimes 2-cleft. Stamens 4, didynamous, ascending under the upper lip, the upper pair longer than the lower; anthers 2-celled, the sacs divaricate; style 2-cleft at the summit; ovary deeply 4-parted. Nutlets ovoid, smooth. [From Moldavia.]
About 35 species, natives of the northern hemisphere. Only the following are known in North America. Type species: Dracocephalum Moldavica L. Corolla 2-3 times as long as the calyx; clusters mostly axillary.
1. M. parviflora.
Corolla scarcely exceeding the calyx; clusters mostly terminal, dense.
2. M. Moldavica.
Dracocephalum parviflorum Nutt. Gen. 2: 35. 1818.
Annual or biennial, somewhat pubescent, or glabrous; stem rather stout, usually branched, 6'-2i° high. Leaves lanceolate, ovate, or oblong, slender-petioled, serrate, or the lower incised, acute or obtuse at the apex, rounded or narrowed at the base, thin, 1'-3' long; clusters dense, many-flowered, crowded in dense terminal spikes, and sometimes also in the upper axils; bracts ovate to oblong, pectinate with awn-pointed teeth, shorter than or equalling the calyx; pedicels 1"-2" long; upper tooth of the calyx ovate-oblong, longer than the narrower lower and lateral ones, all acuminate; corolla light blue, scarcely longer than the calyx.
In dry gravelly or rocky soil, Quebec and Ontario to Alaska, New York, Iowa, Missouri and Arizona. May-Aug.
Dracocephalum Moldavica L. Sp. Pl. 595. 1753.
Annual, puberulent; stem erect, usu-illy widely branched, 1°-2 1/2° high. Leaves Oblong or linear-oblong, dentate or somewhat incised, obtuse at the apex, usually narrowed at the base, 1'-2' long, 2"-6" wide; clusters loose, few-flowered, commonly numerous, mostly axillary; bracts narrowly oblong, usually shorter than the calyx, deeply pectinate with aristate teeth; pedicels 2 "- 4" long; calyx slightly curved, the 2 lower teeth somewhat shorter than the 3 broader equal upper ones; corolla 2-3 times as long as the calyx.
In a canon near Spring View, Nebr. Also in northern Mexico. Introduced from central Europe. June-Aug.