The Families of Flowering Plants
The Families of Flowering Plants | |
Including Sesamaceae R. Br. ex Berchtold & Presl
Excluding 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 terminal inflorescence unit cymose. Inflorescences axillary; dichasia or cymes. Flowers bracteate (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. Stamens 4; 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 pistil 2–8 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.
Seedling. Germination phanerocotylar.
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 (1998) Eudicot; core Eudicot; Asterid; Euasterid I; 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).
Illustrations. • Technical details (Sesamum, Pedalium). • Technical details (Sesamum).
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, summaries of attributes within groups of taxa, geographical distribution, genera included in each family, classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG), and notes on the APG classification.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 10th April 2008. http://delta-intkey.com’.
