Solanum nigrum L. - Black Nightshade.
Taxonomic position.Family Solanaceae Juss., genus Solanum L.
Biological group.Spring annual weed.
Morphology and biology.Plant is 8-90 cm in height, dark green, herbaceous, with scattered hairs or almost glabrous. Tap root is short and spindle-shaped. Stem is upright or ascending, branched, with costate branches. Leaves are plumpish, glabrous or with scarce setiform decumbent hairs along main ribs, ovate or almost triangular, sinuate-serrate; seldom almost entire, narrowed into sharp tip, widely decurrent at short petiole. Inflorescences are usually extra-axillary, very seldom some of them are opposite to leaves; they are umbel-like or slightly racemose-corymbose, consisting of 3-8 flowers. Flower stalks have scattered pubescence. Peduncles are more densely pubescent, drooping during fruiting. Calyx is glabrous or having non-dense accumbent hairs. Corolla up to the middle consists of 5 lobes; it is twice or three times as long as calyx, whitish or slightly violet. Fruit is berry, globular, black, brownish-green or yellow. Seeds are irregularly-oval, compressed laterally, lustreless, stramineous. This plant flowers in June-September, bears fruit in July-November. Maximum productivity is up to 280,000 seeds. Minimum temperature for seed germination is 10-12°C, maximum is 34-36°C, optimum is 24-26°C. Seeds germinate from depths of 0.5-1 cm.
Distribution.European part of the Former Soviet Union, the Caucasus, Central Asia, Western Siberia, the Far East. Distributed also in Scandinavia, Middle and Atlantic Europe, Mediterranean, Iran, India, China, Japan, North Africa; an adventive plant in North America.
Ecology.This plant prefers rich, cultivated, well-moistened soils, but can even grow on saline soils and in stony places.
Economic significance.S.nigrum is a segetal weed of mainly tilled crops; it is rarely found in close-growing crops, such as grain and fodder crops. This plant is especially abundant in cotton fields; it is often found in gardens, vegetable gardens, in ruderal places (near roads, houses, in waste dumps), sometimes in bush thickets along rivers. The abundance of S.nigrum decreases from the west to the east and from the south to the north. This weed can be a host plant for Synchitrium endobioticum, the pathogen of potato wart. All parts of the plant, except ripe fruits, contain toxic glycoalkaloid solanine, as well as alkaloids betaine and saponin, and tannins; leaves contain ascorbic acid and carotene; fruits contain up to 36% fatty oil which is suitable for paintwork industry. Young leafy shoots and ripe fruits of S.nigrum are used in medicine. S.nigrum has significance as a food source, its young leaves are used in salads; ripe fruits are used for preparation of jam and filling for pies, and also in wine, spirit and canning industries. Control measures include thorough main and pre-sowing soil treatments, harrowing of tilled crops, eradication of S.nigrum before flowering, mowing of this weed in uncultivated places.
Reference citations.Chebotar, A.A., ed. 1989. Plants of steppes and limestone slopes, and weeds. Kishinev: Shtiintsa. 304 p. (in Russian).
Keller, B.A., ed. 1935. Weed plants of the USSR. V. 4. Moscow-Leningrad: AN SSSR. 414 p. (in Russian).
Melnichuk, O.S. & Kovalivska, G.M. 1972. Atlas of the most widespread weeds of the Ukraine. Kiev: Urozhai, p. 27-28 (in Ukrainian).
Nikitin, V.V. 1983. Weed plants of the USSR flora. Leningrad: Nauka. 454 p. (in Russian).
Shishkin, B.K. & Bobrov, E.G., ed. 1955. Flora of the USSR. V.22. Moscow-Leningrad: AN SSSR. 861 p. (in Russian).
Ulyanova, T.N. 1998. Weed plants in flora of Russia and other CIS countries. St.Petersburg: VIR. 343 p. (in Russian).
Visyulina, O.D., ed. 1970. Weeds of Ukraine (reference-identification guide). Kiev: Naukova Dumka. 508 p. (in Ukrainian).
Volkov, A.N., ed. 1935. Areas of distribution of the major weed plants in the USSR. Moscow-Leningrad: Publishing House of Kolkhoz & Sovkhoz Literature. 153 p. (in Russian).