The genera of Leguminosae-Caesalpinioideae & Swartzieae
Afrointsia Taub. ex Dalla Torre & Harms, Afrazelia Pierre, Pahudia Miq.
Type species: A. africana Sm.
Habit and leaf form. Trees; unarmed.
Phyllotaxy spiral. The leaves compound; pinnate; paripinnate. The leaflets few per leaf; opposite or sub-opposite; petiolulate; with markedly twisted petiolules; rather markedly asymmetrical, or symmetrical or nearly so; with a predominant midrib; with a strong, continuous marginal nerve. Stipules basally connate (into an intrapetiolar scale, the upper parts free and caducous). Stipels present (rarely), or absent.
Inflorescence and floral morphology. The inflorescences terminal; branched; of racemose units; panicles (of racemes). The flowers not distichous. Bracts absent at anthesis. Bracteoles present; small, not enclosing the flower buds; absent at anthesis, or persistent beyond anthesis (rarely); not valvate; free.
The flowers large; hermaphrodite; very irregular; not pentamerous throughout; departing from pentamery in the calyx and in the corolla, or in the calyx, in the corolla, and in the androecium; white or green, or coloured. Floral tube length relative to total hypanthium + calyx length 0.25 (rarely), or 0.5, or 0.75 (rarely). Hypanthium present; more or less elongate, cupular, or tubular. Calyx 4; covering the rest of the flower in bud; polysepalous; more or less regular, or markedly irregular; members imbricate. Corolla present; very irregular; 1, or 1–5 (rarely); including greatly reduced members, or without greatly reduced members; polypetalous, or monopetalous (with one large orbicular or reniform petal). Petals clawed (the large one only), or sessile; white, or white and red. Disk absent. The androecium comprising 3–8 members; declinate, or not declinate; with united members, or members all free of one another; members markedly unequal; including staminodia, or comprising only fertile stamens. The staminodia if present, 2–4; small. Fertile stamens 3–8. Anthers attached well above the base of the connective; dehiscing longitudinally. Ovary stipitate; eccentric, with the stipe adnate. Stigma dilated. Ovules numerous.
Fruit, seed and seedling. Fruit a two-valved pod; without markedly twisting or enrolling valves; becoming woody. The mature valves without prominent venation. Seeds non-endospermic; arillate; with a straight or slightly oblique radicle; amyloid-positive. Cotyledons of Type 4; with a vascular system ramified throughout; epigeal.
Transverse section of lamina. Leaves with conspicuous phloem transfer cells in the minor veins. Druses common in the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis absent. Leaf girders absent. Laminae dorsiventral. Mesophyll without unaligned fibres or sclereids. Minor veins mainly with abundant accompanying fibres.
Leaf lamina epidermes. Epidermal crystals not seen either adaxially or abaxially. Simple unbranched hairs common, or not seen. No compound or branched eglandular hairs seen. Capitate glands not seen. Hooked hairs not seen. Cassieae-type leaf pseudo-glands not seen. Expanded and embedded hair-feet absent. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted; medium-thin to thin. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; conspicuously pitted in optical section; scarcely staining with safranin, or staining normally with safranin; medium-thin.
Wood anatomy. Wood without septate fibres; storied, or not storied; without normal intercellular canals; without traumatic canals. Intervascular pits medium to large.
Pollen ultrastructure. Tectum reticulate; strongly irregularly coarse-reticulate. Length of colpi greater than one half pole to pole distance, or less than one half pole to pole distance. Foot layer of pollen wall smooth.
Cytology. Basic chromosome number, x = 12. 2n = 24.
Species number and distribution. About 12 species. Tropical Africa, Asia.
Tribe. Detarieae; Amherstieae clade of Bruneau et al. (2008).
Comments. Widely cultivated.
Miscellaneous. Illustrations: • A. bracteata: Hook. Ic. Pl. (1844). • A. bracteata, floral diagram: Baillon, Histoire des Plantes 2 (1870). • A. bella and A. pachyloba: Aubréville, Flore du Gabon (1968). • A. xylocarpa: li shu gang (2005). • A. bracteata, floral diagram: Baillon, Histoire des Plantes 2 (1870). • A. africana: Engler & Drude, Pflanzenwelt Afrikas 9 (1915). • A. rhomboidea, e.m. scanned pollen (Graham & Barker, 1981).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or 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 or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classification. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1993 onwards. The genera of Leguminosae-Caesalpinioideae and Swartzieae: descriptions, illustrations, identification, and information retrieval. In English and French. Version: 22nd March 2017. delta-intkey.com/caes’.