| # The genera of Leguminosae-Caesalpinioideae and Swartzieae |

L. Watson and M.J. Dallwitz

### Dimorphandra Schott

Type species: D. exaltata Schott.

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

Phyllotaxy spiral. The leaves compound; bipinnate; with opposite or sub-opposite leaflets. The leaflets many per leaf (often hairy); opposite or sub-opposite; petiolulate to sessile to sub-sessile; without noticeably twisted petiolules; symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’. Stipules absent or early caducous or very inconspicuous in mature leaves; membranous. Stipels absent.

Inflorescence and floral morphology. The inflorescences unbranched, or branched; when branched, of racemose units; simple racemes (which are sometimes spicate), or panicles. The flowers not distichous. Bracts caducous, small, absent at anthesis. Bracteoles absent; absent at anthesis.

The flowers small; hermaphrodite; actinomorphic; pentamerous. Floral tube length relative to total hypanthium + calyx length if present, about 0.2–0.75. Hypanthium present (but very short), or absent, the androecium hypogynous; when present, campanulate. The perianth comprising distinct calyx and corolla. Calyx lobes 5; not covering the rest of the flower in bud; gamosepalous; more or less regular; members imbricate. Corolla present; regular; 5; without greatly reduced members; polypetalous. Petals spathulate, sessile; imbricate; imbricate-ascending. Disk absent. The androecium comprising 10 members; not declinate; members all free of one another; members all more or less equal in length, or markedly unequal; including staminodia. The staminodia 5; sometimes shorter than the fertile members with which they alternate. Fertile stamens 5 (opposite the petals). Anthers attached at the base of the connective (but sagittate); dehiscing longitudinally. Ovary sessile or subsessile, or stipitate; free. Stigma not dilated (the style short). Ovules numerous.

Fruit, seed and seedling. Fruit flat, linear to broadly falcate, elastically a two-valved pod, or indehiscent; straight, or curved; becoming woody, or not becoming woody. Seeds endospermic; with a straight or slightly oblique radicle; amyloid-negative.

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 present, or absent. Leaf girders absent. Laminae dorsiventral. Mesophyll without unaligned fibres or sclereids. Minor veins mainly with abundant accompanying fibres.

Leaf lamina epidermes. Epidermal crystals present, or not seen either adaxially or abaxially; prisms. 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; of medium thickness. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis papillate interveinally, or not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; not conspicuously pitted in optical section; staining normally with safranin; of medium thickness.

Wood anatomy. Intervascular pits very small.

Pollen ultrastructure. Tectum punctate; smooth punctate, or puncticulate. 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. About 27 species. Tropical America.

Tribe. Caesalpinieae.

Miscellaneous. Illustrations: • Dimorphandra vernicosa: Fl. Brasiliensis 15 (1870). • Dimorphandra speciosa (= ?), floral details: Baillon, Histoire des Plantes 2 (1870). • Dimorphandra coccinea: leaflet, abaxial epidermis. • Dimorphandra pennigera, 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: 4th August 2019. delta-intkey.com’.

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