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The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Gigasiphon Drake del Cast.

~ Bauhinia s. str.

Tournaya Schmitz

Habit and leaf form. Trees; unarmed.

Phyllotaxy distichous, or spiral. The leaves ostensibly simple; palmately veined. Stipules absent or early caducous or very inconspicuous in mature leaves; membranous.

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

The flowers hermaphrodite; pentamerous; coloured. Floral tube length relative to total hypanthium + calyx length about 0.5. Hypanthium present; long- tubular. Calyx not covering the rest of the flower in bud; gamosepalous; more or less regular, or markedly irregular; members not imbricate. Corolla present; regular; 5; without greatly reduced members (the five members much the same size and shape); polypetalous. Petals somewhat clawed, or sessile; imbricate; imbricate-ascending; white, or yellow. The androecium comprising 10 members; members all free of one another; members markedly unequal; comprising only fertile stamens. Fertile stamens 10. Anthers attached well above the base of the connective; dehiscing longitudinally. Ovary stipitate; free. Stigma not dilated. Ovules numerous.

Fruit, seed and seedling. Fruit a two-valved pod; straight; not becoming woody. The mature valves with conspicuous, prominent, raised venation, or without prominent venation; conspicuous venation not predominantly longitudinal. Seeds non-endospermic; arillate (the hilum crescentic); with a straight or slightly oblique radicle.

Transverse section of lamina. Druses absent from the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis absent. Leaf girders absent. Laminae 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 absent. Basally bent hairs present. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted; medium-thick. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; conspicuously pitted in optical section; staining normally with safranin; medium-thin.

Pollen ultrastructure. Tectum striate; interwoven striate. Length of colpi greater than one half pole to pole distance.

Cytology. Basic chromosome number, x = 13.

Species number and distribution. 3 species (G. gossweileri, G. humblotianum and G. macrosiphon). Philippines, New Guinea.

Tribe. Cercideae.

Miscellaneous. Illustrations: • G. macrosiphon: Brenan, Fl. Tropical East Africa (1967). • G. schlechteri, 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. delta-intkey.com/caes’.

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