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The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Gymnocladus Lam.

Type species: G. dioica (L.) Koch (G. canadensis Lam.).

Habit and leaf form. Trees, or shrubs; leaves and inflorescences crowded on ‘short shoots’; unarmed.

Phyllotaxy spiral (with supernumerary axillary buds). The leaves compound (with entire leaflets); bipinnate; with alternate pinnae; with alternate leaflets, or with opposite or sub-opposite leaflets and with alternate leaflets. The leaflets petiolulate; ovate or oblong, symmetrical or nearly so; with a predominant ‘midrib’. Stipules absent or early caducous or very inconspicuous in mature leaves; leafy, or membranous. Stipels present, or absent.

Inflorescence and floral morphology. The inflorescences terminal; unbranched, or branched; whn branched, of racemose units; simple racemes, or panicles. The flowers not distichous. Bracts absent at anthesis. Bracteoles absent; absent at anthesis.

The flowers hermaphrodite, or hermaphrodite and unisexual (dioecious or polygamomonoecious); pentamerous, or not pentamerous throughout; departing from pentamery sometimes in the corolla; white or green, or coloured. Floral tube length relative to total hypanthium + calyx length about 0.5. Hypanthium present; 6–12 mm long, tubular to campanulate. The perianth comprising distinct calyx and corolla. Calyx 5; not covering the rest of the flower in bud; polysepalous (the sepals narrow); more or less regular; members not imbricate. Corolla present; oblong, regular to slightly irregular; exceeding the calyx, 4, or 5 (the adaxial petal sometimes absent); without greatly reduced members; polypetalous. Petals sessile; imbricate; imbricate-ascending (i.e., the adaxial one inside when present); white, or red. Disk absent. The androecium comprising 10 members; members all free of one another; members markedly unequal (in two unequal rows, the short ones alternating with the sepals and the longer ones with the corolla); comprising only fertile stamens. Fertile stamens 10. Anthers attached well above the base of the connective; dehiscing laterally; dehiscing longitudinally. Ovary vestigial of absent in male flowers, in female-fertile flowers sessile or subsessile; free. Stigma dilated (bilobed to capitate on the shortish, straight style). Ovules numerous.

Fruit, seed and seedling. Fruit sessile, oblong, turgid or sub-terite, a follicle (opening only along the placental suture); straight to curved (sub-falcate); filled with pulp between the seeds; not becoming woody. The mature valves without prominent venation. Seeds endospermic; not arillate; with a straight or slightly oblique radicle; amyloid-negative; with galactomannan. Cotyledons not flat; of Type 4; with a vascular system in one plane; epigeal.

Transverse section of lamina. Druses absent from the mesophyll. Mesophyll secretory cavities absent. Leaf girders absent.

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 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, or markedly sinuous in high-focus optical section; conspicuously pitted; thin. Stomata adaxially very rare. Abaxial: Abaxial stomata not predominantly paracytic (anomcytic, actinocytic). Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating, or markedly sinuous in high-focus optical section; conspicuously pitted in optical section; scarcely staining with safranin; thin.

Wood anatomy. Wood without septate fibres; not storied.

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

Cytology. Basic chromosome number, x = 14. 2n = 28.

Species number and distribution. 5 species (e.g., G. burmanicus, G. chinensis, G. dioica). Assam, Burma, China, North America.

Tribe. Caesalpinieae.

Comments. Widely cultivated.

Miscellaneous. Illustrations: • G. chinensis: Hook. Ic. Pl. 15 (1883–85). • G. dioica, 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.’.