The families of flowering plants.
IncludingSesamaceae R. Br. ex Berchtold & PreslExcluding Martyniaceae,Trapellaceae
Habit and leaf form. Herbs (mostly), or shrubs (rarely). Mesophytic to xerophytic (mostly inhabiting shores and deserts). Leaves opposite (at least below); simple. Lamina dissected, or entire; when dissected, pinnatifid, or runcinate; pinnately veined; cross-venulate. Leaves exstipulate.
Leaf anatomy. Hydathodes present (sometimes), or absent. Stomata present; mainly confined to one surface, or on both surfaces; anomocytic. Hairs present; eglandular.
Lamina dorsiventral. Minor leaf veins without phloem transfer cells (Ceratotheca).
Stem anatomy. Cork cambium present; initially superficial. Secondary thickening developing from a conventional cambial ring. Xylem with libriform fibres. Vessel end-walls simple. Wood partially storied (VPI). Pith with diaphragms (sometimes, in Pedalium), or without diaphragms.
Reproductive type, pollination. Plants hermaphrodite. Pollination entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in cymes. The ultimate inflorescence unit cymose. Inflorescences axillary; dichasia or cymes. Flowersbracteate (the bracts with axillary abortive flowers functioning as nectaries); very irregular. The floral irregularity involving the perianth and involving the androecium. Flowers 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present.
Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous (forming a lobed tube); blunt-lobed; with the median member posterior. Corolla 5; 1 whorled; gamopetalous; imbricate; unequal but not bilabiate, or bilabiate; spurred (sometimes), or not spurred.
Androecium 5. Androecial members adnate (to the corolla tube); markedly unequal; free of one another; 1 whorled. Androecium including staminodes. Staminodes 1 (the posterior member); in the same series as the fertile stamens; representing the posterior median member; non-petaloid. Fertile stamens representing the posterior-lateral pair and the anterior-lateral pair. Stamens4; inserted near the base of the corolla tube; didynamous; reduced in number relative to the adjacent perianth; oppositisepalous; alternating with the corolla members. Anthers connivent (in pairs), or separate from one another; dehiscing via longitudinal slits; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate, or T-shaped. Anther wall initially with more than one middle layer; of the ‘dicot’ type. Tapetum glandular. Pollen shed in aggregates (Sesamothamnus), or shed as single grains; when aggregated, in tetrads. Pollen grains aperturate; (3–)5–15 aperturate; colpate; 2-celled.
Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil2–8 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 2–4 locular (but often with false septa). Locules secondarily divided by ‘false septa’, or without ‘false septa’. Gynoecium median; stylate. Styles 1; attenuate from the ovary; much longer than the ovary. Stigmas 1–2; 2 lobed; wet type; papillate; Group III type. Placentation axile. Ovules 1 per locule (Josephinia), or 2–50 per locule (to ‘many’); pendulous, or horizontal, or ascending; anatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped (elongated). Hypostase present. Endosperm formation cellular. Endosperm haustoria present; chalazal and micropylar. Embryogeny onagrad.
Fruit non-fleshy (often with hooks, or prickly); dehiscent, or indehiscent; a capsule, or a nut. Capsules loculicidal. Seeds thinly endospermic, or non-endospermic. Endosperm oily. Seeds with amyloid. Cotyledons 2. Embryo straight.
Physiology, biochemistry. Not cyanogenic. Iridoids detected; ‘Route II’ type (normal and decarb.). Verbascosides detected (2 genera). Proanthocyanidins absent. Ellagic acid absent. Saponins/sapogenins absent. Aluminium accumulation not found.
Peculiar feature. The funicles not as in Acanthaceae.
Geography, cytology. Sub-tropical to tropical. Africa, Madagascar, India, Southeast Asia, Malaysia, Australia.
Taxonomy.Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Lamiiflorae; Scrophulariales. Cronquist’s Subclass Asteridae; Scrophulariales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order Lamiales.
Species 50. Genera 13; Ceratotheca, Dicerocaryum, Harpagophytum, Holubia,Josephinia, Linariopsis, Pedaliodiscus, Pedalium, Pterodiscus,Rogeria, Sesamothamnus, Sesamum, Uncarina.
Economic uses, etc. Commercial edible oil from Sesamum (benne).