Glechoma hederacea L. (Nepeta glechoma Benth., N. hederacea (L.) Trev.)

A polycarpic, aromatic, often purplish, softly hairy or nearly glabrous perennial herb. Flowering shoots 10–30 (–60) cm long, square in section and ascending or erect. Non-flowering stems also square in section, creeping and rooting at many, but not all, nodes. Leaf laminae 4–35 (–80) × 6–40 (–80) mm, reniform to ovate–cordate, obtuse or subacute and coarsely crenate. Petioles highly variable in length from 10 mm in grassland to over 200 mm in woodland with dense canopy cover and dense ground vegetation. Bracteoles 1–1.5 mm, shortly hispid or pubescent. Flowers zygomorphic and hypogynous, borne in few (2–5)-flowered secund axillary whorls, the bracts not differing from the foliage leaves. Calyx tubular or tubular-campanulate, 15-veined, not gibbous at base, and somewhat two-lipped. Upper lip of the corolla flat with three triangular acuminate teeth that are 0.2–0.3 times as long as the tube. Lower lip with two teeth. Corolla tube narrowly obconical, straight and hairy within at the base of lower lip. Corolla (6–) 15–22 (–25) mm, usually blue–violet with purple spots on the lower lip; rarely pink or white. Stamens four, two long and two short, borne on corolla tube and lying below upper lip; anther cells at right angles to each other, each opening by a separate slit. Ovary four-celled and deeply four-lobed, each cell with one ovule. Style gynobasic, its branches equal. Hermaphrodite and male-sterile forms of flowers occur, the latter usually with smaller corollas than hermaphrodite flowers, and much-reduced, pollen-less stamens that are often included in the corolla tube. Clones usually bear either only hermaphrodite or only male-sterile flowers, but in rare cases both types are found on the same individual (Price 1991). Each flower produces a maximum of four obovoid, slightly angled, smooth nutlets with a mean air-dry mass of 0.69 mg (n = 100). Each is slightly angled owing to pressure exerted by the adjacent developing nutlets before dispersal, and each bears a grey protuberance which may be an elaiosome. The dimensions of the seed are 1.9 × 1.1 mm. Glechoma serbica Halácsy & Wettst., which has been recorded in former Jugoslavia, is probably an ecological modification of G. hederacea (Fl. Eur. 3). The southern counterpart of G. hederacea in Europe is ssp. hirsuta (Waldst. & Kit.) F. Hermann, sometimes referred to as G. hirsuta (Elias 1979, 1983). This has denser and longer hairs and longer calyx teeth than G. hederacea, and the corolla is pale blue. It has been recorded in Albania, Austria, Bulgaria, the Czech Republic, Greece, Hungary, Italy, former Jugoslavia, Poland, Rumania, central and south-west Russia, Sardinia and Sicily (Fl. Eur. 3). Intermediates, which are presumably hybrids between G. hederacea and G. hirsuta, sometimes occur (Fl. Eur. 3). In eastern Asia a more or less distinct, short-pubescent race occurs that is called ssp. grandis (A. Gray) Hara [also var. grandis A. Gray and var. longituba (Nakai) Kuprian] (Hultén 1971). In North America the variety micrantha Moricand [or var. parviflora (Benth.) House] is distinguished (Hultén 1971).