The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: S. borneensis Stapf.
Habit and leaf form. Trees; without specialized short shoots; unarmed.
Phyllotaxy spiral. The leaves compound; variably pinnate to bipinnate; when bipinnate, with opposite or sub-opposite pinnae; with opposite or sub-opposite leaflets; when simply pinnate, paripinnate. The leaflets few per leaf; opposite or sub-opposite; petiolulate; 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. Stipels absent.
Inflorescence and floral morphology. The inflorescences spiciform, axillary and terminal; unbranched and branched; of racemose units; simple racemes, fascicles, and panicles. The flowers not distichous. Bracts persistent beyond anthesis. Bracteoles absent; absent at anthesis.
The flowers small; hermaphrodite; actinomorphic; pentamerous. Floral tube length relative to total hypanthium + calyx length 0.5–0.75. Hypanthium present (but slight), or absent, the androecium hypogynous. The perianth comprising distinct calyx and corolla. Calyx 5 (the sepals pellucid-glandular); not covering the rest of the flower in bud; gamosepalous; more or less regular (the lobes very short and rounded, much exceeded by the corolla); members imbricate. Corolla present; regular; 5; without greatly reduced members; very shortly gamopetalous. Petals sessile; oblong, pellucid-glandular, imbricate; imbricate-ascending. Disk absent. The androecium comprising 10 members; not declinate; members all free of one another; members markedly unequal (alternating longer and shorter); comprising only fertile stamens. Fertile stamens 10. Anthers attached at the base of the connective (but basally sagittate, and with a deciduous apical gland); dehiscing longitudinally. Ovary stipitate; free. Stigma small, not dilated. Ovules few (2).
Fruit, seed and seedling. Fruit a two-valved pod; becoming woody. The mature valves with conspicuous, prominent, raised venation; conspicuous venation not predominantly longitudinal. Seeds with a straight or slightly oblique radicle.
Transverse section of lamina. Leaves without conspicuous phloem transfer cells in the minor veins. Druses absent from the mesophyll. Mesophyll secretory cavities (gland-dots) common; epithelium-lined. 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. 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; medium-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; medium-thin.
Pollen ultrastructure. Tectum punctate; smooth punctate, or puncticulate. Length of colpi greater than one half pole to pole distance (without a margocolpus).
Species number and distribution. 4 species (S. borneensis, S. densiflora, S. hildebrandii, S. schmutzii). Borneo, Malaya, Philippines, Lesser Sunda Is..
Miscellaneous. Illustrations: • S. borneensis: Hook Ic. Pl. 28 (1905).
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’.