| # The genera of Leguminosae-Caesalpinioideae and Swartzieae |

L. Watson and M.J. Dallwitz

### Melanoxylon Schott

Perittium Vogel

Type species: M. brauna Schott.

Habit and leaf form. Trees; unarmed.

Phyllotaxy spiral. The leaves compound; pinnate; imparipinnate; with adaxially grooved rachides. The leaflets many per leaf; opposite or sub-opposite; petiolulate; without noticeably twisted petiolules; symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’. Stipels absent.

Inflorescence and floral morphology. The inflorescences terminal; branched; of racemose units; panicles (comprising large racemes). The flowers not distichous. Bracts absent at anthesis. Bracteoles present; absent at anthesis.

The flowers hermaphrodite; pentamerous. Hypanthium present; obliquely cupular, or campanulate. The perianth comprising distinct calyx and corolla. Calyx 5; covering the rest of the flower in bud; polysepalous; more or less regular (the lowermost sepal not modified); members imbricate. Corolla present; slightly irregular (the adaxial, inner one slightly dissimilar from the rest); 5; without greatly reduced members; polypetalous. Petals broadly orbicular, spreading; 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; comprising only fertile stamens. Fertile stamens 10 (the filaments villous at their bases). Anthers oblong, uniform, attached well above the base of the connective; dehiscing introrsely; dehiscing longitudinally. Ovary long sessile or subsessile; free. Stigma tiny, truncate-concave. Ovules numerous.

Fruit, seed and seedling. Fruit a two-valved pod; compressed, curved (broadly oblong-falcate); internally septate; without markedly twisting or enrolling valves; leathery, becoming woody to not becoming woody (or only somewhat so). The mature valves without prominent venation. Seeds compressed, with a falcate wing at the apex 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 absent. Leaf girders absent. 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. 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; not conspicuously pitted; medium-thick. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating, or markedly sinuous in high-focus optical section; not conspicuously pitted in optical section; scarcely staining with safranin, or staining normally with safranin; thin.

Wood anatomy. Wood storied.

Pollen ultrastructure. Tectum reticulate; finely to moderately regularly reticulate. Length of colpi greater than one half pole to pole distance (no margocolpus). Foot layer of pollen wall smooth.

Species number and distribution. 2 species (M. brauna and M. speciosum). Tropical South America.

Tribe. Caesalpinieae.

Miscellaneous. Illustrations: • Melanoxylon brauna (as braunia): 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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