The genera of Leguminosae-Caesalpinioideae & Swartzieae
Baryxylum Lour., Brasilettia DC. ex O. Kuntze
Type species: P. dubium (Spreng.) Taub.
Habit and leaf form. Tall trees; leaves and inflorescences crowded on short shoots; armed, or unarmed.
Phyllotaxy spiral. The leaves compound; bipinnate; with opposite or sub-opposite pinnae; with opposite or sub-opposite leaflets; with adaxially grooved rachides. The leaflets small, many per leaf; petiolulate, or sessile to sub-sessile. Stipules small, absent or early caducous or very inconspicuous in mature leaves (caducous); membranous. Stipels absent.
Inflorescence and floral morphology. The inflorescences terminal; branched; of racemose units; panicles (of racemes). The flowers not distichous. Bracts narrow to lanceolate, caducous, absent at anthesis. Bracteoles absent; absent at anthesis.
The flowers hermaphrodite; pentamerous; coloured. Floral tube length relative to total hypanthium + calyx length about 0.25. Hypanthium present; shortly cupular. The perianth comprising distinct calyx and corolla. Calyx 5; covering the rest of the flower in bud; polysepalous; more or less regular to markedly irregular (the segments subequal); members imbricate. Corolla present; slightly irregular; spreading, 5; without greatly reduced members; polypetalous. Petals orbicular, slightly unequal, very imbricate; imbricate-ascending; yellow. Disk absent. The androecium declinate; members all free of one another; comprising only fertile stamens. Fertile stamens 10 (commonly with basally pilose filaments). Anthers attached well above the base of the connective; dehiscing introrsely. Ovary sessile or subsessile to stipitate; free. Stigma dilated (broadly peltate, the style filiform). Ovules few to numerous.
Fruit, seed and seedling. Fruit indehiscent; not internally septate; narrowly winged longitudinally; 2 winged (i.e., along both sutures); elongate or elongate-lanceolate, compressed, not becoming woody. The mature valves with conspicuous, prominent, raised venation. Seeds non-endospermic; with a straight or slightly oblique radicle; amyloid-negative. Cotyledons of Type 2; epigeal.
Transverse section of lamina. Leaves without conspicuous phloem transfer cells in the minor veins. Druses common in the mesophyll. Mesophyll secretory cavities (gland-dots) common, or absent; without a lining of epithelium. Adaxial hypodermis absent. Leaf girders absent. Laminae dorsiventral. Mesophyll without unaligned fibres or sclereids. Minor veins mainly with abundant accompanying fibres, or lacking accompanying fibrous tissue.
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 present, or absent; all medium to thick-walled; hair feet all simple, without vertical walls. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; conspicuously pitted; of medium thickness. Stomata adaxially very rare. Abaxial: Abaxial stomata not predominantly paracytic (imperfect-paracytic, anomcytic). Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; conspicuously pitted in optical section; scarcely staining with safranin; thin.
Wood anatomy. Wood with septate fibres; not storied. Intervascular pits very small.
Pollen ultrastructure. Tectum reticulate; finely to moderately regularly reticulate, or strongly irregularly coarse-reticulate. Length of colpi greater than one half pole to pole distance, or less than one half pole to pole distance. Foot layer of pollen wall with obvious projections.
Cytology. Basic chromosome number, x = 13, or 14. 2n = 26, or 28.
Species number and distribution. About 10 species. Tropical.
Comments. Widely cultivated.
Miscellaneous. Illustrations: • P. dubium (as vogelianum): Fl. Brasiliensis 15 (1870). • P. pterocarpum: Ding Hou, Fl. Malesiana 12 (1995). • P. pterocarpum (as inerme): Schery, Ann. Miss. Bot. Gard. 38 (1951). • P. africanum, 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: 22nd March 2017. delta-intkey.com/caes’.