The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Distemonanthus Benth.

Type species: D. benthamianus Baill.

Habit and leaf form. Trees; unarmed.

Phyllotaxy spiral. The leaves compound; pinnate; imparipinnate. The leaflets few per leaf; alternate; petiolulate; without noticeably twisted petiolules; 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 developing before the leaves, axillary and terminal; branched; seemingly of cymose units; panicles. Bracts absent at anthesis. Bracteoles absent; absent at anthesis.

The flowers hermaphrodite; not pentamerous throughout; departing from pentamery in the corolla; coloured. Floral tube length relative to total hypanthium + calyx length 0.25. Hypanthium present; saucer-shaped to cupular (shortly turbinate). The perianth comprising distinct calyx and corolla. Calyx (4–)5; covering the rest of the flower in bud; polysepalous; markedly irregular (the adaxial pair larger than the abaxials); members imbricate. Corolla present; slightly irregular (comprising the slightly larger, lanceolate adaxial petal and two somewhat smaller, more linear laterals); 3; without greatly reduced members; polypetalous. Petals slightly imbricate; imbricate-ascending; yellow. The androecium comprising 5 members; members all free of one another; members markedly unequal; including staminodia. The staminodia 3; inserted opposite the lateral petals. Fertile stamens 2 (inserted opposite the adaxial sepals, between the upper and lateral petals, the one opposed to the vexillum shortly lanceolate, the others linear-attenuate). Anthers attached at the base of the connective; dehiscing via pores or short slits. Ovary shortly stipitate; eccentric, with the stipe adnate (located opposite the adaxial sepals). Stigma not dilated. Ovules few.

Fruit, seed and seedling. Fruit compressed, thin, indehiscent; not internally septate; becoming woody. The mature valves with conspicuous, prominent, raised venation; conspicuous venation reticulate, not predominantly longitudinal. Seeds with a straight or slightly oblique radicle; amyloid-negative.

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. Laminae dorsiventral. Mesophyll without unaligned fibres or sclereids. Minor veins mainly with abundant accompanying fibres.

Leaf lamina epidermes. Epidermal crystals present; druses. Simple unbranched hairs common; scabrid. No compound or branched eglandular hairs seen. Capitate glands not seen. Hooked hairs present. Cassieae-type leaf pseudo-glands present. Expanded and embedded hair-feet absent. Basally bent hairs present. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted; of medium thickness. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic to not predominantly paracytic (paracytic, imperfect-paracytic and anomcytic). Abaxial epidermis papillate interveinally; with papillae over-arching the stomata. Abaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted in optical section; scarcely staining with safranin; thin.

Wood anatomy. Wood with septate fibres; storied; without normal intercellular canals; without traumatic canals. Intervascular pits medium to large.

Pollen ultrastructure. Tectum reticulate; rugulose reticulate. Length of colpi greater than one half pole to pole distance.

Cytology. Basic chromosome number, x = 12. 2n = 24.

Species number and distribution. 1 species (D. benthamianus). Tropical West Africa.

Tribe. Cassieae.

Miscellaneous. Illustrations: • D. benthamianus: Engler, Pflanzenwelt Afrikas (1910). • D. benthamianus, floral diagram: Baillon, Histoire des Plantes 2 (1870). • D. benthamianus leaflet: abaxial epidermis.

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.’.