The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Polystemonanthus Harms

Type species: P. dinklagei Harms.

Habit and leaf form. Trees; unarmed.

The leaves compound; large, pinnate; paripinnate (5–7 pairs). The leaflets few per leaf; opposite or sub-opposite; petiolulate; without noticeably twisted petiolules; oblong-elliptic, puberulous below, symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’. Stipules absent or early caducous or very inconspicuous in mature leaves; membranous. Stipels absent.

Inflorescence and floral morphology. The inflorescences terminal; branched; of racemose units; racemose panicles. The flowers not distichous. Bracteoles present; relatively large and enclosing the flower buds (rather thick, broadly oval, with a median keel ending in a broad, thick glandular apiculus); persistent beyond anthesis; valvate.

The flowers hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx and in the androecium. Hypanthium present; thick, asymmetrically more or less cupular, or campanulate. The perianth comprising distinct calyx and corolla. Calyx 4; covering the rest of the flower in bud; gamosepalous to polysepalous (comprising three free sepals and two partially joined); more or less regular to markedly irregular; members imbricate (the sepals silky outside, broadly oval or obovate-oval and rounded, the outermost one broad-based and the others somewhat narrowed to their bases or shortly clawed). Corolla present; slightly irregular (the petals almost equal in length but differing somewhat in shape); 5; without greatly reduced members; polypetalous. Petals clawed (the outer two long clawed, the lateral pair shortly clawed, the inner one with a narrow limb); imbricate; imbricate-ascending. Disk absent. The androecium comprising at least 25–50 members; not declinate; members all free of one another; members all more or less equal in length (with long filaments); comprising only fertile stamens. Fertile stamens very numerous, at least 25–50. Anthers attached at the base of the connective (but sagittate at base); dehiscing longitudinally. Ovary densely silky-hairy, stipitate; eccentric, with the stipe adnate (adnate towards the base of the hypanthium). Stigma terminating the rather long style, minute, not dilated. Ovules numerous (10–12).

Fruit, seed and seedling. Fruit a two-valved pod; compressed, shortly stipitate and apiculate, straight; narrowly winged longitudinally, or not noticeably winged; becoming woody. The mature valves without prominent venation. Seeds not arillate; with a straight or slightly oblique radicle.

Transverse section of lamina. Leaves with 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, or lacking accompanying fibrous tissue.

Leaf lamina epidermes. Epidermal crystals not seen either adaxially or abaxially. Simple unbranched hairs common; smooth. 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; (at least some of them) thin-walled; hair feet (at least some of them) complex with vertical walls. Adaxial: Adaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted; thin. 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; conspicuously pitted in optical section; staining normally with safranin; of medium thickness.

Pollen ultrastructure. Tectum punctate; smooth punctate, or puncticulate. Length of colpi greater than one half pole to pole distance.

Species number and distribution. 1 species (P. dinklagei). Tropical West Africa.

Tribe. Detarieae (Amherstieae of Cowan and Polhill 1981); Amherstieae clade of Bruneau et al. (2008).

Miscellaneous. Illustrations: • P. dinklagei, with Oxystigma buchholzii and Cyanothyrsus soyauxii (= Daniellia): Bot. Jahrb. 26. • P. dinklagei, 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.’.