The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: A. insignis (Benth.) Endl.
Habit and leaf form. Trees; unarmed.
Phyllotaxy spiral. The leaves compound, or ostensibly simple (the upper ones); when simple, pinnately veined with a predominant midrib; mostly pinnate; other than the simple ones, imparipinnate. The leaflets opposite or sub-opposite; petiolulate; without noticeably twisted petiolules; symmetrical or nearly so; pinnately veined, with a predominant midrib. Stipules present, persistent and conspicuous in mature leaves; membranous. Stipels absent.
Inflorescence and floral morphology. The inflorescences axillary (racemes), or terminal (panicles); unbranched, or branched; simple racemes, or panicles. The flowers not distichous. Bracts absent at anthesis. Bracteoles absent; absent at anthesis, or persistent beyond anthesis.
The flowers showy; hermaphrodite; definitely not papilionaceous (cf. Flora Brasiliensis (1870), despite (e.g.) Hutchinson's description); not pentamerous throughout; departing from pentamery in the androecium, or in the calyx and in the androecium; white or green. Floral tube length relative to total hypanthium + calyx length about 0.3. Hypanthium present; short, saucer-shaped to cupular. Calyx 2–5; covering the rest of the flower in bud; Swartzieae type (closed before flowering, splitting more or less irregularly into valvate lobes or teeth); gamosepalous; more or less regular, or markedly irregular; members not imbricate. Corolla present; very irregular; 5; without greatly reduced members; polypetalous. Petals imbricate; imbricate-ascending (as illustrated in the Flora Brasiliensis floral diagram); white. The androecium comprising about 26–60 members (numerous); members all free of one another; members all more or less equal in length; comprising only fertile stamens. Fertile stamens 26 (or more: numerous). Anthers attached well above the base of the connective; dehiscing longitudinally. Ovary stipitate; free. Stigma not dilated. Ovules few.
Fruit, seed and seedling. Fruit a follicle, or a two-valved pod (?); without markedly twisting or enrolling valves; becoming woody. Seeds with an inflexed radicle.
Transverse section of lamina. Leaves without conspicuous phloem transfer cells in the minor veins. Druses absent from the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis absent. Leaf girders common (the veins transcurrent). 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 not seen. No compound or branched eglandular hairs seen. Capitate glands not seen. Expanded and embedded hair-feet absent. Adaxial: Adaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted; medium-thick. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted in optical section; staining normally with safranin; thick.
Wood anatomy. Wood storied. Intervascular pits medium to large.
Pollen ultrastructure. Tectum punctate, or reticulate; smooth punctate, or puncticulate; rugulose reticulate. Length of colpi greater than one half pole to pole distance.
Species number and distribution. About 15 species. Tropical South America.
Comments. Widely cultivated.
Miscellaneous. Illustrations: • A. latifolia: Fl. Brasiliensis 15 (1870).
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’.