The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: E. usambarense Harms.
Habit and leaf form. Trees; unarmed.
Phyllotaxy spiral. The leaves compound; pinnate; paripinnate. The leaflets many per leaf to few per leaf; opposite or sub-opposite; petiolulate; without noticeably twisted petiolules; symmetrical or nearly so; pinnately veined, with a predominant midrib; without a continuous marginal nerve. Stipels absent.
Inflorescence and floral morphology. The inflorescences branched; of racemose units; panicles. The flowers not distichous. Bracteoles present; relatively large and enclosing the flower buds; absent at anthesis, or persistent beyond anthesis; valvate.
The flowers hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx, in the corolla, and in the androecium. Floral tube length relative to total hypanthium + calyx length about 0.25–0.5. Hypanthium present; cupular. Calyx 6–7; not covering the rest of the flower in bud; polysepalous; more or less regular; members imbricate. Corolla present; slightly irregular; 6–7; without greatly reduced members; polypetalous. Petals all clawed. The androecium comprising 12–13 members; members all free of one another; members markedly unequal; including staminodia. The staminodia about 5–10 (?); shorter than and alternating with the fertile stamens, with imperfect anthers. Fertile stamens 6–8. Anthers attached well above the base of the connective; dehiscing longitudinally. Ovary villous and stipitate; free. Stigma not dilated (the style base hairy). Ovules few to numerous (5–6 in E. usambarense).
Fruit, seed and seedling. Fruit a two-valved pod (this obovate or obovate-oblong, with the rounded apex shortly mucronate); not internally septate; without markedly twisting or enrolling valves; becoming woody. The mature valves with conspicuous, prominent, raised venation to without prominent venation; conspicuous venation if present, not predominantly longitudinal. 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 absent. Laminae isobilateral, with adaxial and abaxial palisades, or 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; 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 common and widespread, or adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; not conspicuously pitted in optical section; staining normally with safranin; thin.
Pollen ultrastructure. Tectum striate; reticulate striate. Length of colpi greater than one half pole to pole distance.
Species number and distribution. 2 species (E. gabunense and E. usambarense). Tropical Africa.
Tribe. Detarieae (Amherstieae of Cowan and Polhill 1981); Amherstieae clade of Bruneau et al. (2008).
Miscellaneous. Illustrations: • E. usambarense: Bot. Jahrb. 40 (1907).
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. delta-intkey.com/caes’.