The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: S. parahybum (Vell.) Blake (S. excelsum Vogel).
Habit and leaf form. Tall trees; unarmed.
Phyllotaxy spiral. The leaves large, compound; bipinnate (with several pairs of pinnae); with opposite or sub-opposite pinnae; with opposite or sub-opposite leaflets; with adaxially grooved rachides. The leaflets numerous, many per leaf; petiolulate; symmetrical or nearly so; pinnately veined, with a predominant midrib; without a continuous marginal nerve. Stipules absent or early caducous or very inconspicuous in mature leaves (caducous); membranous. Stipels absent.
Inflorescence and floral morphology. The inflorescences axillary (racemes), or terminal (panicles); unbranched and branched; of racemose units; simple racemes and panicles. The flowers not distichous. Bracts small, absent at anthesis. Bracteoles absent.
The flowers hermaphrodite; pentamerous; coloured. Floral tube length relative to total hypanthium + calyx length about 0.25. Hypanthium present; asymmetrically cupular. The perianth comprising distinct calyx and corolla. Calyx 5; covering the rest of the flower in bud; polysepalous; more or less regular (the sepals reflexing, slightly unequal); members imbricate. Corolla present; slightly irregular; 5; without greatly reduced members; polypetalous. Petals all clawed (ovate or rounded above the claws); slightly unequal, imbricate; imbricate-ascending; yellow. The androecium comprising 10 members; declinate to not declinate (scarcely declinate, the adaxial member embraced by the adaxial petal); members all free of one another (the filaments basally scabrid); ambiguously including staminodia, or comprising only fertile stamens (depending on interpretation of the uppermost stamen with its smaller anther). The staminodia if thus interpreted, 1. Fertile stamens 9, or 10. Anthers attached well above the base of the connective; dehiscing introrsely; dehiscing longitudinally. Ovary sessile or subsessile to stipitate; eccentric, with the stipe adnate. Stigma not dilated (the style filiform). Ovules numerous.
Fruit, seed and seedling. Fruit flat, oblong-cuneate, one-seeded with the seed in a papery endocarp, opening via an apical suture; not becoming woody. The mature valves with conspicuous, prominent, raised venation; conspicuous venation not predominantly longitudinal. Seeds endospermic; with a straight or slightly oblique radicle; amyloid-negative; with galactomannan. Cotyledons flat; of Type 4; with a vascular system in one plane; epigeal.
Transverse section of lamina. 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 lacking accompanying fibrous tissue.
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 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; not conspicuously pitted; thick. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; not conspicuously pitted in optical section; staining normally with safranin; thin.
Wood anatomy. Wood with septate fibres; not storied.
Pollen ultrastructure. Tectum reticulate; finely to moderately regularly reticulate. Length of colpi greater than one half pole to pole distance (without a margocolpus).
Cytology. Basic chromosome number, x = 13. 2n = 26.
Species number and distribution. 1–2 species (S. amazonicum, S. parahyba). Central America to Brazil.
Comments. Widely cultivated.
Miscellaneous. Illustrations: • S. parahyba (as excelsum): Fl. Brasiliensis 15 (1870). • S. parahyba: Schery, Ann. Miss. Bot. Gard. 38 (1951). • S. parahyba, 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’.