The genera of Leguminosae-Caesalpinioideae & Swartzieae
Type species: R. amazonicum (Ducke) Ducke.
Habit and leaf form. Large trees; unarmed.
Phyllotaxy spiral. The leaves compound; pinnate; imparipinnate; with adaxially grooved rachides. The leaflets few per leaf; opposite or sub-opposite; without noticeably twisted petiolules. Stipels absent.
Inflorescence and floral morphology. The inflorescences terminal; branched; of racemose units; panicles (of few-flowered racemes). The flowers not distichous. Bracts very small, caducous, absent at anthesis. Bracteoles present; small, not enclosing the flower buds; very small and caducous, absent at anthesis.
The flowers hermaphrodite; pentamerous; coloured. Floral tube length relative to total hypanthium + calyx length about 0.25. Hypanthium present; cupular. Calyx 5; not covering the rest of the flower in bud; deciduous, polysepalous; members imbricate. Corolla present; slightly irregular; 5; without greatly reduced members; polypetalous. Petals subequal, clawed (broadly expanded above the claws); yellow. The androecium comprising 10 members; not declinate; members all free of one another (with glabrous filaments); comprising only fertile stamens. Fertile stamens 10. Anthers glabrous, attached well above the base of the connective; dehiscing introrsely. Ovary silky-hairy, shortly stipitate; free. Stigma small.
Fruit, seed and seedling. Fruit a two-valved pod (tardily, not elastically dehiscent); flat, linear-oblong, straight; not internally septate; without markedly twisting or enrolling valves; thinly leathery-valved, not becoming woody. Seeds keeled on one edge; 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 absent. Adaxial hypodermis absent. Leaf girders common (the veins transcurrent). 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 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; 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-thick.
Wood anatomy. Wood not storied.
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. 2 species (R. amazonicum, R. stenopetalum). Brazil.
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’.