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The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Didelotia Baill.

Zingania A. Chev., Toubaouate Aubrév. and Pellegr.

Type species: D. africana Baill.

Habit and leaf form. Trees; unarmed.

Phyllotaxy spiral. The leaves compound (usually), or ostensibly simple (rarely); when simple, pinnately veined with a predominant midrib; when compound, i.e. usually, pinnate, or bifoliolate; paripinnate. The leaflets many per leaf, or few per leaf; opposite or sub-opposite; sessile to sub-sessile; markedly asymmetrical to symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’; without a continuous marginal nerve. Stipules present, persistent and conspicuous in mature leaves; connate. Stipels absent.

Inflorescence and floral morphology. The inflorescences terminal; branched; of racemose units; few flowered panicles. The flowers not distichous. Bracts absent at anthesis. Bracteoles present; relatively large and enclosing the flower buds; persistent beyond anthesis; rounded, valvate.

The flowers hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx, or in the corolla, or in the androecium (in various combinations); coloured. Hypanthium present; cupular. The perianth comprising distinct calyx and corolla, or exclusively petaline, or entirely vestigial. Calyx present to absent; more or less obsolete, (0–)4–5; not covering the rest of the flower in bud; polysepalous; members not imbricate. Corolla present to absent; slightly irregular; usually small, subulate, (3–)5; polypetalous. Disk present and conspicuous. The androecium comprising 4–6 members; members all free of one another; members all more or less equal in length to markedly unequal (the filaments inflexed in the bud, soon exserted); including staminodia, or comprising only fertile stamens (?). Fertile stamens 4–5(–6). Anthers attached well above the base of the connective; dehiscing longitudinally. Ovary sessile or subsessile; free (with a slender, somewhat eccentric style). Stigma not dilated (“obsolete"). Ovules few to numerous (biseriate).

Fruit, seed and seedling. Fruit a two-valved pod (flat, oblong-oblanceolate); straight; valves twisting and enrolling during dehiscence; becoming woody. The mature valves with conspicuous, prominent, raised venation to without prominent venation; conspicuous venation usually predominantly longitudinal (with 1–2 subconspicuous median nerves). Seeds not arillate; with a straight or slightly oblique radicle. Cotyledons epigeal.

Transverse section of lamina. Leaves with conspicuous phloem transfer cells in the minor veins. Druses common in the mesophyll, or absent from 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. No compound or branched eglandular hairs seen. Capitate glands not seen. Hooked hairs not seen. Cassieae-type leaf pseudo-glands not seen. Adaxial: Adaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted; thick. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. 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; staining normally with safranin; medium-thick.

Wood anatomy. Wood not storied.

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

Species number and distribution. About 12 species. Tropical Africa.

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

Comments. Descriptive data on floral morphology obtainable from Hutchinson (1964), Cowan and Polhill (1981) and floras consulted are contradictory and inadequate, and scarcely conform with Baillon’s illustration of the type species which is provided here (q.v.).

Miscellaneous. Illustrations: • D. africana: Baillon, Adansonia 5 (1864). • D. unifoliolata: Léonard, in Fl. du Congo Belge (1952). • D. morellii, D. unifoliolata and Zenkerella citrina: Aubréville, Flore du Gabon (1968). • D. minutiflora and Taubaouate (= Didelotia) brevipaniculata, Flore du Gabon (1968).

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.’.