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The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Tetrapterocarpon Humbert

Type species: T. geayi Humbert.

Habit and leaf form. Trees and shrubs; unarmed.

Phyllotaxy spiral. The leaves compound; bipinnate (each with a single terminal pinna); with opposite or sub-opposite pinnae, or with opposite or sub-opposite pinnae and with alternate pinnae; with opposite or sub-opposite leaflets and with alternate leaflets (the end ones paired). The leaflets many per leaf (the pinnae with 8–20 alternate or opposite to sub-opposite leaflets); shortly petiolulate; symmetrical or nearly so; with a predominant ‘midrib’. Stipules absent or early caducous or very inconspicuous in mature leaves (caducous); small, membranous. Stipels absent.

Inflorescence and floral morphology. The flowers aggregated into inflorescences. The inflorescences axillary; branched; of racemose units; mostly comprising panicles of dense, spicate racemes. The flowers not distichous. Bracts very small absent at anthesis. Bracteoles present; paired, alternate, small, not enclosing the flower buds (minute); absent at anthesis; not valvate; free.

The flowers very small (2–6 mm in diameter); unisexual (dioecious); actinomorphic; tetramerous, i.e. conspicuously not pentamerous throughout; departing from pentamery in the calyx, in the corolla, and in the androecium; white or green. Floral tube length relative to total hypanthium + calyx length 0.5. Hypanthium present; relatively quite long; cupular and tubular (cupular above, narrowing and pedicel-like below). The perianth comprising distinct calyx and corolla. Calyx present; 4; polysepalous; more or less regular (the sepals equal); members imbricate. Corolla present; regular; 4; without greatly reduced members; polypetalous. Petals sessile; spreading, equal, much exceeding the sepals, imbricate; not papilionaceous, with no recognisable vexillar member; greenish white. The androecium comprising 8 members; not declinate; members all free of one another; members markedly unequal (the staminodes much exceeded by the stamens in male flowers, and shorter than the sterile stamens in female flowers); including staminodia (these alternating with the stamens in male flowers, and with the sterile stamens in female flowers). The staminodia 8 (in female flowers, with the sterile members treated as staminodes additional to the four more reduced ones), or 4 (in male flowers, alternating with the fertile stamens); comprising 4 very small, hairy ones reflexed over the bases of the petals in both male and female flowers, alernating with the four sterile members in females and with the fertile stamens in males. Fertile stamens in male flowers only 4. Anthers attached well above the base of the connective (sagittate below); dehiscing longitudinally. Ovary stipitate; compressed-fusiform, upcurved, free (reduced to a pistillode in male flowers). Stigma in female flowers, dilated (reniform-capitate and bilobed, the style short and upcurved). Ovules solitary.

Fruit, seed and seedling. Fruit short, compressed, comprising a central fusiform, conspicuously winged seed chamber, indehiscent; not internally septate (the chamber single-seeded); winged longitudinally and broadly papery-winged all round; 4 winged (these papery, the lower pair forming a broad, continuous wing all around the fruit, the two upper wings narrower and shorter); membranous, not becoming woody. Seeds endospermic; not arillate; with a straight or slightly oblique radicle. Cotyledons flat.

Transverse section of lamina. 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; 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 absent. Basally bent hairs present. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; not conspicuously pitted; medium-thick. Stomata adaxially very rare. Abaxial: Abaxial stomata not predominantly paracytic (actinocytic & cyclocytic). Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; not conspicuously pitted in optical section; staining normally with safranin; of medium thickness.

Pollen ultrastructure. Tectum punctate; rugulose punctate. Length of colpi greater than one half pole to pole distance (without a margocolpus).

Species number and distribution. 2 species (T. geayi and T. septentrionalis). Madagascar.

Tribe. Caesalpinieae.

Miscellaneous. Illustrations: • T. geayi, 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.’.