The genera of Leguminosae-Caesalpinioideae & Swartzieae
As re-circumscribed by Wieringa (1999) to include most species formerly assigned to Monopetalanthus Harms.
Type species: A. cynometroides Oliv.
Habit and leaf form. Small to large trees, or shrubs; unarmed.
The leaves compound; pinnate; paripinnate (1–50+ jugate); with rachides terete or slightly grooved adaxially. The leaflets rectangular at their bases, many per leaf; opposite or sub-opposite; petiolulate, or sessile to sub-sessile; markedly asymmetrical; palmately nerved; with a strong, continuous marginal nerve (in that the very asymmetric midrib forms a marginal nerve along the upper edge, except in A. cynometroides, A. djumaensis and A. marginervatus where there is a flange of lamina very asymmetrically disposed beyond it). Stipules absent or early caducous or very inconspicuous in mature leaves; membranous; connate (completely fused, with numerous closely spaced veins). Stipels absent.
Inflorescence and floral morphology. The inflorescences axillary (sometimes strobiliform and shorter than the subtending leaves), or terminal; unbranched, or branched; when branched, of racemose units; simple racemes, or panicles. The flowers not distichous. Bracts densely parallel-veined, glabrous within, absent at anthesis, or persistent beyond anthesis (scarious and early caducous in Aphanocalyx sensu stricto). Bracteoles present (velvety); relatively large and enclosing the flower buds; persistent beyond anthesis; valvate.
The flowers hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx and in the corolla, or in the calyx, in the corolla, and in the androecium. Floral tube length relative to total hypanthium + calyx length 0.01–2. Hypanthium present (comprising fused perianth and androecium); cupular (sometimes very short). The perianth comprising distinct calyx and corolla, or exclusively petaline. Calyx present, or absent; when recognisable, 0–5; not covering the rest of the flower in bud; more or less regular to markedly irregular (often with 2 segments connate to the middle, accompanied by 3 minute teeth); members not imbricate. Corolla present; very irregular (with the clawed-spathulate adaxial petal exceeding the calyx); 1, or 2–4 (the lateral and abaxial members often much reduced or wanting); usually including greatly reduced members; polypetalous, or monopetalous. Petals clawed (i.e., the adaxial one), or sessile; white, or yellow. The androecium comprising (9–)10 members; with united members (all but the free adaxial one having basally united filaments); members all more or less equal in length; comprising only fertile stamens. Fertile stamens 9–10. Anthers attached well above the base of the connective; dehiscing longitudinally (often with dorsal teeth). Ovary sessile or subsessile to stipitate (with the style insertion more or less centric); free (the style filiform, basally hairy). Stigma dilated. Ovules few (1–5(-6)).
Fruit, seed and seedling. Fruit a two-valved pod (usually only shortly beaked); valves twisting and enrolling during dehiscence; winged longitudinally, or not noticeably winged; if winged, 2 winged; becoming woody. The mature valves with conspicuous, prominent, raised venation, or without prominent venation; conspicuous venation usually predominantly longitudinal (with a lateral nerve close to or adjoining the dorsal wings). Seeds not arillate; with a straight or slightly oblique radicle; amyloid-positive. Cotyledons epigeal (the first seedling leaves opposite).
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 present; all medium to thick-walled; hair feet all simple, without vertical walls. Adaxial: Adaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted; medium-thin to thin. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis papillate interveinally, or not papillate; with the papillae not over-arching the stomata. Abaxial interveinal epidermal cell walls straight, or gently undulating, or markedly sinuous in high-focus optical section; not conspicuously pitted in optical section; staining normally with safranin; thin.
Wood anatomy. Wood without septate fibres; storied; without normal intercellular canals; without traumatic canals. Intervascular pits medium to large.
Species number and distribution. About 15 species. Tropical Africa.
Tribe. Detarieae (Amherstieae of Cowan and Polhill 1981); Amherstieae clade of Bruneau et al. (2008).
Miscellaneous. Illustrations: • A. richardsii (as Monopetalanthus): Brenan, Fl. Tropical East Africa (1967). • A. hedinii, A. microphyllus and A. pectinatus: Aubréville, Flore du Gabon (1968), as Monopetalanthus spp.. • A. cynometroides: Hook. Ic. Pl. XI (1867). • A. cynometroides: Wieringa (1999). • A. djumaensis: Wieringa (1999). • A. ledermannii: Wieringa (1999). • A. margininervatus: Wieringa (1999).
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’.