Lamium amplexicaule L. - Henbit Dead-Nettle.
Systematic position.Family Lamiaceae Lindl., genus Lamium L.
Synonyms.Lamium stepposum Kossko ex Klok.
Biological group.Annual or facultative biennial germiniparous weed.
Morphology and biology.Stems usually numerous, erect or ascending, 10-20 cm high, ramified below, tetrahedral, covered with soft haires in upper part. Cotyledons round-oval, with slightly concave tip, petiolate, tips at base usually not touching each other. Leaves transverse opposite, round-reniform; lower leaf pairs wide apart, long-petiolate; upper leaves sessile, enclosing stem, and reticulate-rugose; margins deeply crenate; all leaves nearly hairless or shortly bristly-haired. Flowers numerous, located in dense axillary whorls. Corolla pink or carmine-red, fluffy-haired on the outside, with thin long tube. Tube 1.1-1.3 cm long, straight or sometimes bent, widened at fauces, hairless inside. Upper labium oblong or ovate, 2-3 mm long, lower labium somewhat shorter than upper one, with dark spots. Nutlets obovate, 2-3 mm long, 1 mm wide, nearly triquetrous, light gray or brown, with big white warty formations. The weight of 1000 nutlets is 0.6-0.8 g. Seeds per plant, 220 (50-300). Seeds keep germinating ability in soil to 5 years. Flowering period in April-September.
Distribution.Western Europe, the Mediterranean, Asia Minor, Iran, the Himalaya, Korea, Japan, North America, North Africa. European part of the former USSR, the Caucasus, Crimea, Central Asia, Western Siberia, Eastern Siberia, the Far East.
Ecology.Likes well-aerated, light, nutrient-rich, sandy loam soils. Shoots emerge at the minimal temperature +4.+6°C, optimum +22.+28°C.
Economic significance.Infests grain and tilled crops, occurs in fallow lands, kitchen gardens, along roads, near habitations. Control measures include careful cultivation of fallow lands, harrowing of winter crops in spring, chemical weeding, cutting on waste lands.
Related references:Anonym. 1996. Weeds in sugar beet. Berlin: Hoehst Schering AgrEvo GmbH. P. 274 (in German, English, Russian, Ukrainian).
Melnichuk, O.S. & Kovalivska, G.M. 1972. Atlas of the most widespread weeds of the Ukraine. Kiev: Urozhai. P. 23-24 (in 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. 116-117 (in Russian).