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The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Eperua Aubl.

Type species: E. falcata Aubl.

Habit and leaf form. Trees; unarmed; shortly without leaves reduced to phyllodes, the leaflets normally well developed and persistent.

Phyllotaxy spiral. The leaves compound; pinnate; imparipinnate (almost, rarely), or paripinnate. The leaflets few per leaf; leathery, opposite or sub-opposite (in few pairs); petiolulate; without noticeably twisted petiolules; symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’. Stipules present, persistent and conspicuous in mature leaves; leafy, or membranous; connate, or not connate. Stipels absent.

Inflorescence and floral morphology. The inflorescences unbranched, or branched; when branched, of racemose units; short, simple racemes, or panicles. The flowers not distichous. Bracts absent at anthesis. Bracteoles present; small, not enclosing the flower buds; absent at anthesis; not valvate; free.

The flowers showy; hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx and in the corolla; white or green, or coloured. Floral tube length relative to total hypanthium + calyx length about 0.25. Hypanthium present (but infilled by nectary tissue,); asymmetrically cupular. The perianth comprising distinct calyx and corolla. Calyx 4; covering the rest of the flower in bud, or not covering the rest of the flower in bud; more or less regular; members imbricate. Corolla present; very irregular; 1, or 1–5; including greatly reduced members, or without greatly reduced members; polypetalous, or monopetalous (with one very broad petal). Petals sessile; white, or red. Disk present and conspicuous. The androecium comprising 10 members; with united members to members all free of one another (free or basally united); members all more or less equal in length, or markedly unequal (then with members alternately longer and shorter); including staminodia, or comprising only fertile stamens. The staminodia 1–5; shorter than the fertile stamens, the anthers imperfect or lacking. Fertile stamens 10, or 5–9. Anthers attached well above the base of the connective; dehiscing longitudinally. Ovary eccentric, with the stipe adnate. Stigma small, but dilated (capitate on the slender, elongate style, which is inflexed in the bud). Ovules numerous.

Fruit, seed and seedling. Fruit a two-valved pod; straight, or curved; becoming woody, or not becoming woody. The mature valves without prominent venation. Seeds non-endospermic; not arillate; with a straight or slightly oblique radicle; amyloid-positive. Cotyledons not flat.

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 common (the veins transcurrent). Laminae dorsiventral. Mesophyll exhibiting fibres or sclereids which are unaligned with the vascular bundles, or without unaligned fibres or sclereids. Minor veins mainly with abundant accompanying fibres.

Leaf lamina epidermes. Epidermal crystals present, or not seen either adaxially or abaxially; druses. 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; thick. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic (sometimes some imperfect-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; thick.

Wood anatomy. Wood without septate fibres; not storied; with normal intercellular canals; without traumatic canals. Intervascular pits medium to large.

Pollen ultrastructure. Tectum reticulate; strongly irregularly coarse-reticulate. Length of colpi less than one half pole to pole distance.

Species number and distribution. 16 species. Tropical South America.

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

Miscellaneous. Illustrations: • Eperua purpurea: Fl. Brasiliensis 15 (1870). • E. jenmanii: Hook. Ic. Pl. 20 (1891. • E. falcata, E. jenmanii, E. leucantha and E. rubiginosa: 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.’.