The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Hoffmannseggia Cavan.

Hoffmanseggia, Larrea Orteg., Melanosticta DC.

Type species: H. falcaria Cav.

Habit and leaf form. Shrubs (only in Africa), or herbs, or climbers or scramblers (rarely); without tendrils; without specialized ‘short shoots’; unarmed (but often very stipitate-glandular).

Phyllotaxy spiral. The leaves compound; bipinnate (ending in a single pinna); with opposite or sub-opposite pinnae; with opposite or sub-opposite leaflets; with rachides adaxially ridged. The leaflets small, not or only sparingly glandular-punctate, many per leaf; petiolulate; without noticeably twisted petiolules. Stipules present, persistent and conspicuous in mature leaves; membranous; small, not connate. Stipels present (small and setaceous), or absent.

Inflorescence and floral morphology. The inflorescences exclusively leaf-opposed or terminal; unbranched; simple racemes. The flowers not distichous. Bracts deciduous, absent at anthesis. Bracteoles absent.

The flowers hermaphrodite; pentamerous; coloured. Floral tube length relative to total hypanthium + calyx length about 0.25. Hypanthium present; saucer-shaped, or cupular. The perianth comprising distinct calyx and corolla. Calyx 5; covering the rest of the flower in bud, or not covering the rest of the flower in bud; polysepalous; markedly irregular (with lowest sepal modified); members not imbricate (valvate). Corolla present; slightly irregular to very irregular (the petals all well developed, but the adaxial member often dissimilar to the rest); 5; without greatly reduced members; polypetalous. Petals sessile; spreading, imbricate; imbricate-ascending (i.e., the adaxial member inside); yellow. Disk absent. The androecium comprising 10 members; members all free of one another; members all more or less equal in length (the filaments often basally glandular); comprising only fertile stamens. Fertile stamens 10. Anthers attached well above the base of the connective; dehiscing introrsely; dehiscing longitudinally. Ovary sessile or subsessile (often with the style incurved and distally clavate); free. Ovules numerous.

Fruit, seed and seedling. Fruit a two-valved pod (in Africa, the valves often glandular or with plumose setae), or indehiscent (in America); subsessile, linear or ovate, straight, or curved; not noticeably winged; not becoming woody. Seeds endospermic, or non-endospermic; with a straight or slightly oblique radicle; amyloid-negative.

Transverse section of lamina. Leaves without 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 isobilateral, with adaxial and abaxial palisades, or dorsiventral. Mesophyll without unaligned fibres or sclereids. Minor veins lacking accompanying fibrous tissue.

Leaf lamina epidermes. Epidermal crystals not seen either adaxially or abaxially. Simple unbranched hairs common; scabrid. No compound or branched eglandular hairs seen. Capitate glands present. Hooked hairs not seen. Cassieae-type leaf pseudo-glands not seen. Expanded and embedded hair-feet absent. Basally bent hairs absent. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted, or not conspicuously pitted; medium-thin to thin. Stomata adaxially common and widespread. Abaxial: Abaxial stomata predominantly paracytic, or not predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; conspicuously pitted in optical section, or not conspicuously pitted in optical section; scarcely staining with safranin; medium-thin to thin.

Pollen ultrastructure. Tectum punctate, or reticulate; smooth punctate, or puncticulate, or rugulose punctate; finely to moderately regularly reticulate. Length of colpi greater than one half pole to pole distance (with a margocolpus). Foot layer of pollen wall smooth.

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

Species number and distribution. About 30 species. America, tropical and southern Africa.

Tribe. Caesalpinieae.

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.’.