Lamium purpureum L. - Red Dead-Nettle, or Purple Dead-Nettle.
Systematic position.Family Lamiaceae Lindl., genus Lamium L.
Biological group.Annual or facultative biennial germiniparous weed.
Morphology and biology.Stems prostrate or ascending, up to 30 cm high, ramified, tetrahedral, covered with red bloom in upper part. Cotyledons round-oval, with slightly concave tip, petiolate, with overlapping basal tips. Leaves transverse opposite, soft-haired, wrinkled, markedly veined, irregularly crenate at margins; lower leaves petiolate, ovate-cordate, upper leaves ovate, nearly sessile, often lilac-purple. Flowers purple-red, sometimes pink, located in multiflorous axillary whorls. Calyx bell-shaped, two times shorter than corolla, hairless or haired. Corolla with thin, long tube widened at fauces. Upper labium oblong or ovate, lower labium with lilac spots, 3-lobed. Nutlets obovate, 2-2.5 mm long, 1-1.3 mm wide, nearly triquetrous, gray, with white tubercles. The maximal fruitfulness of one plant is 1700 nutlets. The weight of 1000 nutlets is 0.75-1 g. Flowering period in April-October.
Distribution.Western Europe, Asia Minor, northern Iran, Japan, North America. European part of the former USSR, the Caucasus, Western Siberia, Eastern Siberia.
Ecology.Grows on almost all soils, particularly on well-aerated chalky loams with adequate water supply.
Economic significance.Infests grain crops, occurs in orchards and kitchen gardens, along roads, on fallow and waste lands, near habitations. Control measures include removing of stubble, under-winter plowing, chemical weeding, cutting before flowering on waste lands.
Related references:Anonym. 1996. Weeds in sugar beet. Berlin: Hoehst Schering AgrEvo GmbH. P. 276 (in German, English, Russian, Ukrainian).
Nikitin, V.V. 1983. Weed plants of the USSR flora. Leningrad: Nauka. P. 309 (in Russian).
Shishkin, B.K., ed. 1954. Flora of the USSR. V. 21. Moscow-Leningrad: AN SSSR. P. 130-131 (in Russian).
Shishkin, B.K., ed. 1963. Botanical atlas. Moscow-Leningrad: Izd-vo sel'skokhozyaistvennoi literatury, zhurnalov i plakatov. P. 238-239 (in Russian).
Ulyanova, T.N. 1998. Weed plants in the flora of Russia and other FSU states. St.-Petersburg: VIR. P. 257 (in Russian).