Zanthoxylum L.

Scientific Description

Family Rutaceae.

Habit and leaf form. Scandent or erect shrubs, or trees; evergreen, or deciduous; bearing essential oils. Plants prickly, or spiny. Mesophytic, or xerophytic. Leaves alternate; leathery, or ‘herbaceous’; petiolate; non-sheathing; gland-dotted, or not gland-dotted; aromatic; compound; unifoliolate, or ternate, or pinnate; paripinnate, or imparipinnate. Leaflets 1–31. Lateral leaflets alternate, or opposite. Leaf blades pinnately veined, or one-veined. Leaves without stipules, or with stipules. Stipules when present, intrapetiolar; represented by glands. Leaf blade margins entire, or crenate. Leaves without a persistent basal meristem. Stem anatomy. Nodes unilacunar, or tri-lacunar. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers functionally male (gynoecium rudimentary or absent), or functionally female (stamens rudimentary or absent), or hermaphrodite (rarely). Unisexual flowers present, or absent (rarely). Plants dioecious, or monoecious (rarely). Entomophilous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes, or in racemes, or in panicles. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal, or axillary. Flowers bracteate; small; fragrant; regular, or somewhat irregular. The floral asymmetry when noticeable, involving the perianth and involving the androecium (not K). Flowers 6–8 merous (when uniseriate), or 4–5 merous (when biseriate); cyclic. Floral receptacle developing a gynophore (associated with the disk), or with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk present; intrastaminal; annular. Perianth with distinct calyx and corolla, or sepaline, or petaline; 6–10; 1 -whorled, or 2 -whorled; isomerous. Calyx (3–)4, or 5; 1 -whorled; polysepalous, or gamosepalous; imbricate; regular; with the median member posterior. Corolla (3–)4, or 5; 1 -whorled; polypetalous, or gamopetalous; imbricate (the odd petal anterior); regular, or unequal but not bilabiate. Fertile stamens present, or absent (from female flowers). Androecium 4–6. Androecial members unbranched, or branched (? by the splitting of simple primordia); free of the perianth; all equal, or markedly unequal; free of one another, or coherent (? the filaments usually more or less basally connate); 1 - adelphous, or 3–12 - adelphous; 1 -whorled, or 2 -whorled. Stamens 4–6; isomerous with the perianth; oppositisepalous. Anthers dorsifixed, or basifixed (? more or less); versatile; dehiscing via longitudinal slits; introrse, or latrorse; tetrasporangiate. Fertile gynoecium present, or absent (from male flowers). Gynoecium 1–5 carpelled. The pistil when syncarpous, 1–5 celled. Gynoecium apocarpous, or syncarpous (when carpels partially distinct); eu-apocarpous, or semicarpous; superior. Carpel stylate; 2 ovuled. Placentation of the free carpels marginal. Ovary unilocular, or plurilocular; 1–5 locular. Gynoecium stylate. Styles 1, or 3–5; free, or partially joined; apical. Stigmas capitate; wet type, or dry type; papillate, or non-papillate; Group II type, or Group IV type. Placentation when syncarpous, axile. Ovules 2 per locule; pendulous; epitropous; collateral; arillate, or non-arillate; anatropous, or hemianatropous.

Fruit and seed features. Fruit fleshy, or non-fleshy; red, or black; an aggregate, or not an aggregate. The fruiting carpel dehiscent, or indehiscent; a follicle (1–5 distinct or partially connate, 2-valved, follicles). Fruit when syncarpous a schizocarp. Mericarps 1–5; comprising follicles. Fruit 1–5 celled; 1–5 seeded. Seeds ovate to orbicular; endospermic. Embryo well differentiated. Cotyledons 2. Embryo chlorophyllous, or achlorophyllous; straight, or curved, or bent. Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C₃.

Geography, cytology, number of species. A genus of c. 200 species.