Begoniaceae C.A. Agardh.
Habit and leaf form. Herbs (mostly), or shrubs, or lianas. Normal plants. Plants succulent (mostly), or non-succulent. Perennial; with a basal aggregation of leaves, or with neither basal nor terminal aggregations of leaves. Self supporting, or climbing; climbers root climbers. Mesophytic. Leaves small to medium-sized; alternate; spiral, or distichous; flat; herbaceous, or fleshy; petiolate; non-sheathing; simple (usually), or compound; when compound, palmate. Lamina entire (usually), or dissected; generally conspicuously asymmetric; often more or less trapezoid or elephants ear shaped; sometimes palmatifid; palmately veined; cross-venulate. Leaves stipulate. Stipules intrapetiolar; free of one another; scaly, or leafy (often large); caducous, or persistent. Lamina margins entire, or crenate, or serrate. Leaves without a persistent basal meristem.
Leaf anatomy. Leaves with pearl glands (these deciduous). Hydathodes present (occasionally), or absent. Stomata mainly confined to one surface (abaxial, often grouped); anisocytic, or paracytic, or diacytic, or cyclocytic (usually with 36 subsidiaries, these often in two rings).
Adaxial hypodermis commonly present (often of large cells, often of more than one layer). Cystoliths present (commonly), or absent. The mesophyll with sclerencymatous idioblasts, or without sclerenchymatous idioblasts. Minor leaf veins without phloem transfer cells (Begonia).
Stem anatomy. Cork cambium present; initially superficial. Nodes tri-lacunar, or penta-lacunar. Primary vascular tissue comprising a ring of bundles. Cortical bundles present (commonly), or absent. Medullary bundles present (commonly), or absent. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. Included phloem absent. Xylem with libriform fibres; with vessels. Vessel end-walls simple, or scalariform and simple. Pith with diaphragms, or without diaphragms.
Reproductive type, pollination. Fertile flowers functionally male and functionally female. Plants monoecious (the first inflorescence axes usually ending in male flowers, the last and sometimes the penultimate ones in females). Female flowers with staminodes, or without staminodes (androecium very small or lacking). Gynoecium of male flowers absent.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in cymes. The terminal inflorescence unit cymose. Inflorescences axillary (usually), or epiphyllous (two species); dichasia, with bostryx tendency. Flowers small, or medium-sized; somewhat irregular, or very irregular. The floral irregularity involving the perianth, or involving the androecium, or involving the perianth and involving the androecium. Flowers cyclic. Free hypanthium absent.
Perianth petaline; 2, or 4 (commonly), or 25, or 10 (rarely Hillebrandia); free (usually), or joined; 1 whorled (in females and some males, then imbricate), or 2 whorled (in some males, then valvate); when 2, isomerous; more or less different in the two whorls (the outer members larger and covering the inner); white, or cream, or orange, or red, or pink. Corolla 2, or 4, or 5; 1 whorled, or 2 whorled; polypetalous (usually), or gamopetalous; imbricate, or valvate; unequal but not bilabiate.
Androecium (4)50100 (usually many). Androecial members branched, or unbranched; usually many and maturing centripetally; free of the perianth; free of one another, or coherent (connate); when joined, variously 1 adelphous; 25 whorled (usually many whorls). Androecium exclusively of fertile stamens. Stamens (4)50100; diplostemonous to polystemonous. Anthers adnate; dehiscing via pores, or dehiscing via longitudinal slits; extrorse (usually), or latrorse; tetrasporangiate; appendaged (by the elongated connective), or unappendaged. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with one middle layer, or initially with more than one middle layer. Tapetum glandular. Pollen grains aperturate; 3 aperturate; colporate; 2-celled.
Gynoecium 23(6) carpelled (often longitudinally winged). Carpels isomerous with the perianth, or increased in number relative to the perianth. The pistil 23(6) celled. Gynoecium syncarpous; synovarious; inferior. Ovary 23(6) locular. Styles 23(6); free (usually), or partially joined (at the base). Stigmas dry type; papillate; Group II type. Placentation axile. Ovules 1550 per locule (many); non-arillate; anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped. Endosperm formation nuclear. Embryogeny onagrad.
Fruit non-fleshy (usually), or fleshy; dehiscent (usually), or indehiscent; a capsule (usually, usually more or less winged), or a berry. Capsules usually loculicidal. Fruit 25100 seeded (many). Seeds non-endospermic; small. Embryo weakly differentiated to well differentiated (tiny). Cotyledons 2. Embryo straight.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Not cyanogenic. Alkaloids absent (2 species). Iridoids not detected. Proanthocyanidins present, or absent; when present, cyanidin. Flavonols present, or absent; quercetin. Ellagic acid absent (5 Begonia species). Saponins/sapogenins present, or absent. Aluminium accumulation not found. Plants accumulating free oxalates. C3. C3 physiology recorded directly in Begonia.
Geography, cytology. Sub-tropical and tropical. Pantropical, concentrated in America. X = 1021(+).
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Violiflorae; Violales. Cronquists Subclass Dilleniidae; Violales. APG (1998) Eudicot; core Eudicot; Rosid; Eurosid I; Cucurbitales. Species 920. Genera 35; Begonia, Hillebrandia, Symbegonia (Begoniella, Semibegoniella).
Economic uses, etc. Over 130 cultivated ornamental species of Begonia are commercially available.
Illustrations. Technical details (Begonia). Technical details (Begonia).
Cite this publication as: ‘L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000. http://biodiversity.uno.edu/delta/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991) should also be cited (see References).