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| The genera of Leguminosae-Caesalpinioideae and Swartzieae |
Jonesia Roxb. p.p.
Type species: S. indica L.
Habit and leaf form. Trees; unarmed.
Phyllotaxy distichous, or spiral. The leaves compound; pinnate; paripinnate. The leaflets many per leaf (mostly few pairs), or few per leaf; opposite or sub-opposite (sometimes with a pair of wart-like glands at base or apex); petiolulate, or sessile to sub-sessile; without noticeably twisted petiolules; 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; connate (intrapetiolar). Stipels absent.
Inflorescence and floral morphology. The inflorescences lateral or on the older wood; branched; of racemose units; panicles (these corymbose). The flowers not distichous. Bracts small, absent at anthesis to persistent beyond anthesis. Bracteoles present (coloured, much shorter than the floral tube); small, not enclosing the flower buds, or relatively large and enclosing the flower buds; absent at anthesis, or persistent beyond anthesis; not valvate; free.
The flowers hermaphrodite, or unisexual; not pentamerous throughout; departing from pentamery in the calyx and in the corolla, or in the calyx, in the corolla, and in the androecium; coloured. Floral tube length relative to total hypanthium + calyx length about 0.5. Hypanthium present; elongate tubular. The perianth exclusively sepaline (but petaloid). Calyx 4 (the sepals ovate); covering the rest of the flower in bud; polysepalous; more or less regular; members imbricate. Corolla absent. Disk absent. The androecium comprising 3–10 members; with united members to members all free of one another (depicted in illustrations (q.v.) as inserted in a circle on a very short sheath); members all more or less equal in length; including staminodia (represented by tiny vestiges alternating with the stamens), or comprising only fertile stamens (?). Fertile stamens (3–)4–8(–10). Anthers attached well above the base of the connective; dehiscing longitudinally (sometimes hairy apically and/or basally). Ovary stipitate; eccentric, with the stipe adnate. Stigma small but dilated to not dilated (on the filiform style). Ovules numerous.
Fruit, seed and seedling. Fruit a two-valved pod; straight, or curved; valves twisting and enrolling during dehiscence; becoming woody, or not becoming woody. The mature valves with conspicuous, prominent, raised venation, or without prominent venation; conspicuous venation not predominantly longitudinal. Seeds non-endospermic; not arillate; with a straight or slightly oblique radicle; amyloid-positive. Cotyledons of Type 4; with a vascular system ramified throughout.
Transverse section of lamina. Leaves with 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 present; prisms. Simple unbranched hairs not seen. No compound or branched eglandular hairs seen. Capitate glands not seen. Expanded and embedded hair-feet absent. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; 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; conspicuously pitted in optical section; staining normally with safranin; medium-thin.
Wood anatomy. Intervascular pits very small.
Pollen ultrastructure. Tectum punctate; rugulose punctate. Length of colpi greater than one half pole to pole distance.
Cytology. Basic chromosome number, x = 12. 2n = 24.
Species number and distribution. 2 species (S. asoca and S. celebica, with about 8 formerly recognised species reduced to synonymy). Tropical Asia.
Tribe. Detarieae; Amherstieae clade of Bruneau et al. (2008).
Comments. Widely cultivated.
Miscellaneous. Illustrations: • Saraca dives: li shu gang (2005). • Saraca asoca (~ indica), S. celebica, S. indica: Ding Hou, Fl. Malesiana 12 (1995).
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’.
