The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: L. edule H. Perrier.
Habit and leaf form. Much branched shrubs; leaves and inflorescences crowded on short shoots; armed (via the spine-tipped lateral shoots); without leaves reduced to phyllodes, the leaflets normally well developed and persistent.
Phyllotaxy spiral. The leaves compound; pinnate; paripinnate; with rachides adaxially ridged. The leaflets few per leaf (mostly about 3 pairs); very small, eglandular, opposite or sub-opposite; shortly petiolulate; without noticeably twisted petiolules; symmetrical or nearly so; with a predominant midrib; with a strong, continuous marginal nerve. Stipules small, present, persistent and conspicuous in mature leaves; acicular, to 2 mm long; not connate. Stipels represented by hair tufts.
Inflorescence and floral morphology. The inflorescences short, borne laterally on the spine-tipped short-shoots; unbranched; few to many flowered, simple racemes. The flowers not distichous. Bracts thick and spine-like, but caducous and absent at anthesis.
The flowers showy; hermaphrodite; very irregular (zygomorphic, with the upper member slightly larger with the margins of its claw inrolled to form a narrow funnel); pentamerous; having the upper petal lemon yellow, the others whitish. The perianth comprising distinct calyx and corolla. Calyx present; 5; covering the rest of the flower in bud; polysepalous; more or less regular; members narrowly oblong, thich and leathery, not imbricate (valvate). Corolla slightly irregular (the petals subequal); 5; without greatly reduced members. Well developed petals 5. Corolla polypetalous. Petals all clawed (with obovate laminae); very imbricate; imbricate-ascending; subequal, white (the abaxial four), or yellow (the adaxial one, within its white margins). Disk absent. The androecium comprising 10 members; somewhat declinate; members all free of one another; members with slender, basally hairy, long-exserted filaments somewhat exceeding the style, markedly unequal (alternately longer and shorter?); comprising only fertile stamens. Fertile stamens 10. Anthers attached well above the base of the connective; dehiscing introrsely; dehiscing longitudinally. Ovary oblong, velvety-pubescent, sessile or subsessile; free. Stigma not dilated (minutely penicillate on the long, slender style). Ovules numerous.
Fruit, seed and seedling. Fruit pendulous, a two-valved pod (often marbled with drk grey, elastically dehiscent, the seeds 7–16); twisted or somewhat curved; internally septate to not internally septate (or rather, sub-septate, being impressed between the seeds); valves twisting and enrolling during dehiscence; leathery, not becoming woody. The mature valves without prominent venation. Seeds endospermic (the endosperm thin, adnate to the testa); not arillate; with a straight or slightly oblique radicle.
Transverse section of lamina. Leaves without conspicuous phloem transfer cells in the minor veins. Druses common in the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis absent. Leaf girders absent. Laminae 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 (adaxially and abaxially); scabrid. 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 absent. Basally bent hairs absent. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted to not conspicuously pitted; medium-thick. Stomata adaxially common and widespread. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; conspicuously pitted in optical section (in places), or not conspicuously pitted in optical section; brown, scarcely staining with safranin; medium-thick, or of medium thickness.
Species number and distribution. 1 species (L. edule). Madagascar.
Comments. Not widely cultivated (but economic potential under investigation).
Miscellaneous. Illustrations: • L. edule: E. Rakotoarisoa inaturalist.org.
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’.