Solanum L.

Scientific Description

Common name. Nightshades. Family Solanaceae.

Habit and leaf form. Small trees, or shrubs, or lianas, or herbs, or herbaceous climbers (or trailing); resinous, or not resinous. Plants prickly, or spiny, or unarmed. Perennial; plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves. Stem internodes solid. Rhizomatous, or tuberous. Self supporting, or climbing; the climbers stem twiners, or scrambling. Helophytic to xerophytic. Leaves alternate, or alternate to opposite (paired, sometimes often); usually spiral (at least below); ‘herbaceous’, or leathery; petiolate; non-sheathing; simple, or compound; epulvinate; when compound, ternate, or pinnate. Leaf blades dissected (lobed or pinnatisect), or entire; when simple/dissected, pinnatifid; pinnately veined; cross-venulate. Leaves without stipules; without a persistent basal meristem. Leaf anatomy. Hairs present (on stems as well as leaves), or absent (rarely); glandular hairs absent, or present. Extra-floral nectaries absent.

Reproductive type, pollination. Fertile flowers hermaphrodite (usually), or functionally male and functionally female, or functionally male, or functionally female. Unisexual flowers present, or absent (usually). Plants hermaphrodite (usually), or monoecious, or andromonoecious, or dioecious. Male flowers with pistillodes. Entomophilous.

Inflorescence and flower features. Flowers solitary (sometimes), or aggregated in ‘inflorescences’; in cymes (variously modified), or in racemes (raceme-like), or in umbels (umbel-like), or in panicles (panicle-like, or lateral or extra-axillary). The terminal inflorescence unit apparently cymose. Inflorescences terminal (usually), or axillary (initially terminal but soon appears lateral as overtopped by growth of an axillary bud), or leaf-opposed; cymes may be branched and the inflorescence paniculate or corymbose in form or more often be reduced to a simple cyme that may appear racemose or even subumbellate, or may be extremely reduced to 1–2 flowers. Flowers pedicellate (articulate at the base); ebracteate; ebracteolate; small to medium-sized; regular; 5 merous; cyclic; tetracyclic. Free hypanthium present, or absent. Hypogynous disk usually present; intrastaminal. Perianth with distinct calyx and corolla; 10 (mostly), or 8, or 11–20; 2 -whorled; isomerous. Calyx present; (4–)5(–10); 1 -whorled; gamosepalous; blunt-lobed, or toothed; campanulate, or cupuliform, or cyathiform (or rotate); regular (usually); persistent; accrescent, or non-accrescent. Corolla present; (4–)5(–10); 1 -whorled; gamopetalous. Corolla lobes about the same length as the tube to markedly longer than the tube. Corolla contorted and plicate, or imbricate, or valvate, or contorted; rotate (usually, or stellate), or campanulate (broadly); regular; white (less often), or yellow (less often), or purple, or violet, or blue (colour varies with temperature). Fertile stamens present, or absent. Androecial members definite in number. Androecium 5. Androecial members adnate; all equal (usually); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens (4–)5. Staminal insertion in the throat of the corolla tube. Stamens all inserted at the same level; becoming exserted; all more or less similar in shape; reduced in number relative to the adjacent perianth (rarely), or isomerous with the perianth; oppositisepalous (at the base of the throat of the corolla). Filaments appendiculate, or not appendiculate. Anthers separate from one another (AKJ), or connivent (commonly); basifixed (usually); dehiscing via pores (terminal), or dehiscing via short slits, or dehiscing via longitudinal slits (rarely), or dehiscing transversely; introrse (usually, if dehiscence not terminal); tetrasporangiate. Fertile gynoecium present, or absent. Gynoecium 2 carpelled. The pistil 2–4 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 2(–4) locular (sometimes 3–4 via secondary septa). Gynoecium oblique; stylate. Styles 1; attenuate from the ovary; apical. Stigmas 1; 1 - lobed, or 2 - lobed; capitate (or bifid). Placentation axile. Ovules 20–50 per locule (many, numerous, or rarely few); non-arillate; anatropous, or hemianatropous.

Fruit and seed features. Fruit fleshy, or non-fleshy; not spinose; dehiscent, or indehiscent; capsular-indehiscent, or a berry, or a drupe. Capsules septicidal, or loculicidal, or valvular. Fruit 2(–4) celled; 20–100 seeded (usually numerous, sometimes several). Seeds endospermic. Endosperm oily, or not oily. Seeds compressed. Cotyledons 2. Embryo curved (curved through more than a semicircle).

Economic uses, etc. Potato, eggplant and many cultivated ornamentals. Many produce poisonous alkaloids.

Etymology. From the Latin name used by Pliny for S. nigrum, the nightshade.