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The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Diptychandra Tul.

Type species: D. epunctata Tul.

Habit and leaf form. Small trees, or shrubs; unarmed.

Phyllotaxy spiral. The leaves compound; pinnate; paripinnate; with adaxially grooved rachides (finely so). The leaflets few per leaf (bijugate in D. aurantiaca); pelucid-punctate, 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 axillary and terminal; unbranched; lax simple racemes. The flowers not distichous. Bracts absent at anthesis. Bracteoles absent; absent at anthesis.

The flowers small; hermaphrodite; pentamerous; coloured. Floral tube length relative to total hypanthium + calyx length about 0.5. Hypanthium present; cupular. The perianth comprising distinct calyx and corolla. Calyx 5; covering the rest of the flower in bud; not Swartzieae type; polysepalous; more or less regular (the sepals only slightly unequal); members imbricate. Corolla present; regular to slightly irregular; 5; without greatly reduced members; polypetalous. Petals small, ovate; imbricate; imbricate-ascending; yellow. Disk absent. The androecium comprising 10 members; members all free of one another; members all more or less equal in length (the basally pilose filaments biplicate in the bud); comprising only fertile stamens. Fertile stamens 10. Anthers attached well above the base of the connective; dehiscing laterally. Ovary shortly stipitate; free. Stigma not dilated (the style filiform, inflexed). Ovules few.

Fruit, seed and seedling. Fruit a two-valved pod; short to elongated, compressed; not internally septate; not becoming woody (the valves leathery). Seeds non-endospermic (winged unilaterally or all round); with a straight or slightly oblique radicle.

Transverse section of lamina. Druses absent from the mesophyll. Mesophyll secretory cavities (gland-dots) common; without a lining of epithelium. 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; scabrid, or 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. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted; thin. 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 reticulate (pollen tetrads); finely to moderately regularly reticulate. Length of colpi greater than one half pole to pole distance (without a margocolpus). Foot layer of pollen wall smooth, or with obvious projections.

Species number and distribution. 2 species (D. aurantiaca and D. glabra). Brazil, Bolivia, Paraguay.

Tribe. Caesalpinieae.

Miscellaneous. Illustrations: • D. aurantiaca subsp. epunctata, with Cenostigma gardnerianuma: 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: 22nd March 2017.’.