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The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Eurypetalum Harms

Type species: E. tessmannii Harms.

Habit and leaf form. Trees; unarmed.

The leaves compound; pinnate, or bifoliolate; paripinnate. The leaflets few per leaf; opposite or sub-opposite (1- or 2-jugate); petiolulate; with markedly twisted petiolules, or without noticeably twisted petiolules; symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’; without a continuous marginal nerve. Stipules absent or early caducous or very inconspicuous in mature leaves. Stipels absent.

Inflorescence and floral morphology. The inflorescences unbranched and branched; of racemose units; simple racemes and panicles. The flowers not distichous. Bracteoles present; small, not enclosing the flower buds (minute); persistent beyond anthesis; not valvate; free.

The flowers hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx; white or green. Hypanthium present; cupular. The perianth comprising distinct calyx and corolla. Calyx 4; covering the rest of the flower in bud; polysepalous; more or less regular; members imbricate. Corolla present; very irregular (with one large, broadly sub-reniform petal, the others much smaller, rounded, hyaline and scale-like); 5; including greatly reduced members; polypetalous. Petals sessile. Disk absent. The androecium comprising 10 members; with united members (basally shortly joined); members all more or less equal in length; comprising only fertile stamens. Fertile stamens 10. Anthers attached well above the base of the connective; dehiscing longitudinally. Ovary stipitate; free. Stigma conspicuously dilated (capitellate, terminating the short style). Ovules few, or solitary (1–2).

Fruit, seed and seedling. Fruit a two-valved pod; valves twisting and enrolling during dehiscence; becoming woody. The mature valves without prominent venation. Seeds 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 (gland-dots) common; epithelium-lined. 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 not seen. No compound or branched eglandular hairs seen. Capitate glands not seen. Expanded and embedded hair-feet absent. Adaxial: Adaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; conspicuously pitted; of medium thickness. Stomata adaxially common and widespread. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; staining normally with safranin; thin.

Species number and distribution. 3 species (E. batesii, E. tessmannii and E. unijugum). Tropical Africa.

Tribe. Detarieae; Detarieae sensu stricto clade of Bruneau et al. (2008).

Miscellaneous. Illustrations: • E. tessmannii: Bot. Jahrb. 45 (1911). • E. batesii, E. tessmannii and E. unijugum: Aubréville, 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.’.