The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: A. madagascariensis Drake del Castello.
Habit and leaf form. Deciduous trees, or shrubs; unarmed.
The leaves compound; pinnate; paripinnate; with rachides subcylindrical to deeply grooved adxially. The leaflets many per leaf to few per leaf (10–16 or 24–38, with red-brown gland dots); opposite or sub-opposite to alternate; shortly petiolulate; without noticeably twisted petiolules; basally cuneate and somewhat asymmetrical; without a continuous marginal nerve (but with intramarginal nerves). Stipules minute. Stipels absent.
Inflorescence and floral morphology. The inflorescences axillary and terminal; branched; of cymose units; panicles (often compound, with the flowers opening simultaneously). The flowers not distichous. Bracts absent at anthesis. Bracteoles present; paired, small, not enclosing the flower buds; absent at anthesis; not valvate; free.
The flowers small; hermaphrodite; more or less actinomorphic to slightly irregular; not pentamerous throughout; departing from pentamery in the calyx and in the corolla; white or green, or coloured (greenish, creamy white or - in A. mandrarense - red). Hypanthium present; very short to long; cupular to obconical, sometimes long-tapered basally. The perianth exclusively sepaline. Calyx present; 4 (the sepals gland dotted); covering the rest of the flower in bud; polysepalous; more or less regular; members imbricate. Corolla absent. Disk present and conspicuous (towards the apex of the hypanthium). The androecium comprising 10 members; not declinate; members all free of one another; members exserted on filiform filaments, all more or less equal in length to markedly unequal; comprising only fertile stamens. Fertile stamens 10. Anthers attached well above the base of the connective (the didynamous anthers very small); dehiscing laterally. Ovary stipitate; free (central). Stigma minute, not dilated. Ovules numerous (8–16).
Fruit, seed and seedling. Fruit indehiscent (samaroid); without markedly twisting or enrolling valves; winged proximally to the single seed (resembling an Acer fruit, but the one seed distal); 1 winged. Seeds with a straight or slightly oblique radicle.
Transverse section of lamina. Mesophyll secretory cavities (gland-dots) common.
Pollen ultrastructure. Tectum punctate; rugulose punctate. Length of colpi greater than one half pole to pole distance.
Species number and distribution. 3 species (A. madagascariense, A. mandrarense and A. tuberosum). Madagascar.
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’.