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..
Low diffuse creeping herbs, with long-petioled nearly orbicular or reniform crenate leaves, and rather large blue or violet flowers in small axillary verticillate clusters. Calyx oblong-tubular, 15-nerved, oblique at the throat, not 2-lipped, unequally 5-toothed. Corolla-tube exserted, enlarged above, the limb 2-lipped; upper lip erect, 2-lobed or emarginate; the lower lip spreading, 3-lobed, the middle lobe broad, emarginate. the side lobes small. Stamens 4, didynamous, all anther-bearing, ascending under the upper lip of the corolla, not exserted, the upper pair the longer; anther-sacs divergent. Ovary deeply 4-parted. Nutlets ovoid, smooth. [Greek name for thyme or pennyroyal.]
About 6 species of Europe and Asia, the following typical.
Glecoma hederacea L. Sp. Pl. 578. 1753. N. Glechoma Benth. Lab. Gen. & Sp. 485.
1834. N. hederacea B.S.P. Prel. Cat. N. Y. 43.
Perennial, pubescent, the creeping stems leafy, sometimes 18' long, the branches ascending. Lower petioles commonly longer than the leaves; leaves green both sides, 1/2'-1 1/2' in diameter; clusters few-flowered, the flowers 7"-10" long, short-pedicelled; bractlets subulate, shorter than the calyx; calyx puberulent, its teeth acute or lanceolate-acuminate, about one-third as long as the tube; corolla-tube 2-3 times as long as the calyx; upper pair of stamens much longer than the lower.
In waste places, woods and thickets, Newfoundland to Ontario, Minnesota, Oregon, Georgia, Tennessee, Kansas and Colorado. Old names, alehoof, cat's-foot, gill, gill-ale, gill-go-by-the-ground, hayhofe, haymaids, hove, tunhoof, creeping charlie, robin-runaway, gill-run-over, crow-vituals, wild snake-root, hedge-maids. March-May.