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 thin mostly petioled leaves, and small or minute clustered flowers, in terminal bracted spikes. Calyx campanulate or ovoid, 10-nerved, scarcely oblique, enlarging in fruit, not bearded in the throat, 5-toothed, the teeth nearly equal. Corolla-tube little longer than the calyx, straight, or a little curved, the limb oblique, or slightly 2-lipped, 4-lobed; upper lobe erect, concave, emarginate, the 3 others spreading. Stamens 4, divergent, didynamous, ascending, exserted, the upper pair shorter; anthers 2-celled, or the sacs more or less confluent. Style 2-cleft at the summit. Ovary 4-parted. Nutlets ovoid or oblong, tuberculate, or nearly smooth. [Named in honor of J. S. Elsholtz, a Prussian botanist.]
About 20 species, natives of Asia. Type species: Elsholtzia cristata Willd.
Mentha Patrinii Lepech. Nov. Act. Petrop. 13: 336. 1802. E. cristata Willd. in Roem. & Ust. Mag. Bot. 11:3. 1790. Elsholtzia Patrinii Garcke, Garcke, Fl. Dcutsch. Ed. 4, 257. 1858.
Annual, glabrous or nearly so; stems weak, erect or ascending, at length widely branched, 1°-2° high. Leaves long-petioled, ovate or oblong, acute or acuminate at the apex, narrowed at the base, crenate-dentate, 1'-3' long; spikes terminal, very dense, l'-3' high, about ¥ thick; flowers several in the axils of each of the broadly ovate membranous green reticulated mucronate bracts; calyx hirsute, shorter than the bract; corolla 1" long, pale purple.
Notre Dame du Lac, Temiscouata Co., Quebec. Naturalized from Asia. July-Aug.