The genera of Leguminosae-Caesalpinioideae & Swartzieae
~ Dialium. Misspelled Vittienia in earlier versions of this data set and derivatives, as pointed out by Paul van Rijckevorsel (Taxacom 2009).
Type species: U. modesta van Steenis.
Habit and leaf form. Trees; unarmed.
Phyllotaxy spiral. The leaves ostensibly simple (unifoliolate, the petiole thickened at each end); ovate to lanceolate, pinnately veined, with a predominant midrib. Stipules minute, linear, absent or early caducous or very inconspicuous in mature leaves; membranous.
Inflorescence and floral morphology. The inflorescences short, axillary; branched; of cymose units (thyrses); panicles. The flowers not distichous. Bracts absent at anthesis. Bracteoles present; small, not enclosing the flower buds; absent at anthesis.
The flowers hermaphrodite; pentamerous. Hypanthium absent, the androecium hypogynous. Calyx 5; covering the rest of the flower in bud; polysepalous; members imbricate. Corolla present; regular; 5; without greatly reduced members; polypetalous. Disk present and conspicuous (hairy). The androecium comprising 5 members; not declinate; members all free of one another; members all more or less equal in length; comprising only fertile stamens. Fertile stamens 5. Anthers attached at the base of the connective; dehiscing laterally; dehiscing longitudinally. Ovary terete stipitate (the style short, subulate); free. Stigma not dilated. Ovules solitary.
Fruit, seed and seedling. Fruit indehiscent; sub-obliquely globular, to 6 cm diameter, drupaceous (with crustaceous exocarp and pulpy to mealy endocarp). The mature valves without prominent venation. Seeds endospermic; 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 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; 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; conspicuously pitted in optical section; staining normally with safranin; thick.
Species number and distribution. 1 species (U. modesta). Borneo.
Miscellaneous. Illustrations: • U. modesa: Hou et al., 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: 22nd March 2017. delta-intkey.com/caes’.