| # The genera of Leguminosae-Caesalpinioideae and Swartzieae |

L. Watson and M.J. Dallwitz

### Cenostigma Tul.

Type species: C. macrophyllum Tul.

Habit and leaf form. Trees, or shrubs (with stellate indumentum); without specialized ‘short shoots’; unarmed.

Phyllotaxy spiral. The leaves compound; pinnate (3-jugate in C. gardnerianum); paripinnate; with adaxially grooved rachides (finely so). The leaflets leathery; alternate; petiolulate; without noticeably twisted petiolules; symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’. Stipels absent.

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

The flowers rather large; hermaphrodite; pentamerous. Floral tube length relative to total hypanthium + calyx length 0.25. Hypanthium present; cupular. The perianth comprising distinct calyx and corolla. Calyx 5; not covering the rest of the flower in bud; polysepalous; markedly irregular (the abaxial member naviculate and larger); members imbricate. Corolla present; slightly irregular; 5; without greatly reduced members; polypetalous. Petals obovate, imbricate; imbricate-ascending. The androecium comprising 10 members; members all free of one another; members all more or less equal in length (declinate); comprising only fertile stamens. Fertile stamens 10 (the filaments lanate). Anthers attached well above the base of the connective; dehiscing introrsely. Ovary sessile or subsessile; free. Stigma slightly dilated to not dilated. Ovules few.

Fruit, seed and seedling. Fruit oblanceolate, flat, a two-valved pod; straight; thinly filled between the seeds; without markedly twisting or enrolling valves; becoming woody. The mature valves with conspicuous, prominent, raised venation; conspicuous venation not predominantly longitudinal. Seeds non-endospermic; with a straight or slightly oblique radicle.

Transverse section of lamina. Leaves without conspicuous phloem transfer cells in the minor veins. Druses absent from the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis absent. Leaf girders common (the veins transcurrent). 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. Compound or branched eglandular hairs present, or 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. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted; of medium thickness. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; not conspicuously pitted in optical section; staining normally with safranin; thin.

Pollen ultrastructure. Tectum reticulate; finely to moderately regularly reticulate. Length of colpi greater than one half pole to pole distance (with margocolpus-like zones). Foot layer of pollen wall smooth, or with obvious projections.

Species number and distribution. 3 species (C. gardnerianum, C. macrophyllum and C. tocantinum). Brazil, Paraguay.

Tribe. Caesalpinieae.

Miscellaneous. Illustrations: • Cenostigma gardnerianum, with Diptychandra aurantiaca subsp. epunctata: Fl. Brasiliensis 15 (1870).

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: 4th August 2019. delta-intkey.com’.

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