| # The genera of Leguminosae-Caesalpinioideae and Swartzieae |

L. Watson and M.J. Dallwitz

### Dicorynia Benth.

Dicorynea Lindl.

Type species: D. paraensis Benth.

Habit and leaf form. Trees; unarmed.

Phyllotaxy spiral. The leaves compound; pinnate; imparipinnate. The leaflets few per leaf; alternate; petiolulate; without noticeably twisted petiolules; markedly asymmetrical; pinnately veined, with a predominant ‘midrib’. Stipules absent or early caducous or very inconspicuous in mature leaves. Stipels absent.

Inflorescence and floral morphology. The inflorescences terminal; branched; of cymose units; panicles. Bracts absent at anthesis. Bracteoles present; absent at anthesis.

The flowers hermaphrodite; not ‘papilionaceous’; not pentamerous throughout; departing from pentamery in the corolla and in the androecium; white or green. Hypanthium absent, the androecium hypogynous. Calyx 5; covering the rest of the flower in bud; polysepalous; more or less regular; members imbricate. Corolla present; very irregular; 3 (seemingly representing the vexillum and two laterals); without greatly reduced members. Well developed petals 3. Corolla polypetalous. Petals clawed to sessile; imbricate; ambiguously imbricate-ascending to imbricate-descending with the posterior petal (vexillum) outside (the supposed vexillum exterior or contorted); white. Disk absent. The androecium comprising 2 members; members all free of one another; members markedly unequal; comprising only fertile stamens. Fertile stamens 2. Anthers attached at the base of the connective; dehiscing via pores or short slits (and with distal adventitious septa). Ovary sessile or subsessile; free. Stigma not dilated (the style filiform, inflexed). Ovules few.

Fruit, seed and seedling. Fruit 1–2 seeded, indehiscent; not drupaceous; obliquely ovate, plano-compressed; narrowly winged longitudinally (on the upper suture); not becoming woody. The mature valves without prominent venation. Seeds endospermic; with a straight or slightly oblique radicle; amyloid-negative.

Transverse section of lamina. Leaves with conspicuous phloem transfer cells in the minor veins. Druses absent from the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis present. 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; scabrid. No compound or branched eglandular hairs seen. Capitate glands not seen. Hooked hairs present. Cassieae-type leaf pseudo-glands present. Expanded and embedded hair-feet absent. Basally bent hairs present. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; not conspicuously pitted; thin. Stomata adaxially very rare. Abaxial: Abaxial epidermis papillate interveinally; with papillae over-arching the stomata. Abaxial interveinal epidermal cell walls straight, or gently undulating; conspicuously pitted in optical section; staining normally with safranin; thin.

Wood anatomy. Wood without septate fibres; storied; without normal intercellular canals; without traumatic canals. Intervascular pits medium to large.

Pollen ultrastructure. Tectum punctate; smooth punctate, or puncticulate. Length of colpi greater than one half pole to pole distance.

Species number and distribution. 2 species (D. guianensis and the polymorphic D. paraensis). Tropical South America.

Tribe. Cassieae.

Miscellaneous. Illustrations: • Dicorynia paraensis: Fl. Brasiliensis 15 (1870). • Dicorynia guianensis: abaxial epidermis of leaflet.

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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