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The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Dansera van Steenis

~ Dialium.

Type species: D. procera van Steenis.

Habit and leaf form. Trees; unarmed.

Phyllotaxy spiral. The leaves ostensibly simple (1-foliolate, the petiole jointed at base and apex); with a predominant midrib. Stipules absent or early caducous or very inconspicuous in mature leaves; membranous. Stipels absent.

Inflorescence and floral morphology. The inflorescences axillary and terminal; branched; seemingly of cymose units; panicles. The flowers not distichous. Bracts minute, absent at anthesis (caducous). Bracteoles present; minute, small, not enclosing the flower buds; absent at anthesis, or persistent beyond anthesis.

The flowers small; hermaphrodite; not pentamerous throughout; departing from pentamery in the calyx, in the corolla, and in the androecium; white or green. Hypanthium absent, the androecium hypogynous. The perianth exclusively sepaline. Calyx 3; covering the rest of the flower in bud; polysepalous; markedly irregular (having the outer lobe hooded); members imbricate. Corolla absent. Disk absent. The androecium comprising 6 members; members all free of one another; members all more or less equal in length; comprising only fertile stamens. Fertile stamens 6. Anthers attached at the base of the connective; dehiscing via pores or short slits. Ovary sessile or subsessile; free (the style straight, its tip recurved). Stigma dilated (capitate). Ovules few.

Fruit, seed and seedling. Fruit with crustaceous exocarp and pulpy endocarp, indehiscent; drupaceous. The mature valves with conspicuous, prominent, raised venation to without prominent venation; conspicuous venation sometimes oblique or reticulate, not predominantly longitudinal.

Transverse section of lamina. Druses absent from the mesophyll. Mesophyll secretory cavities absent. Adaxial hypodermis absent. Leaf girders absent. Laminae dorsiventral. Minor veins mainly with abundant accompanying fibres.

Leaf lamina epidermes. Epidermal crystals present (adaxially); in irregular clumps. Simple unbranched hairs common; scabrid. No compound or branched eglandular hairs seen. Capitate glands not seen. Hooked hairs present. Cassieae-type leaf pseudo-glands present. Expanded and embedded hair-feet absent. Basally bent hairs absent. Adaxial: Adaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; conspicuously pitted. Stomata adaxially very rare. Abaxial: Abaxial stomata predominantly paracytic. Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls markedly sinuous in high-focus optical section; conspicuously pitted in optical section; staining normally with safranin.

Pollen ultrastructure. Tectum punctate; rugulose punctate. Length of colpi greater than one half pole to pole distance. Foot layer of pollen wall with obvious projections.

Species number and distribution. 1 species (D. procera (Dialium procerum)). Sumatra.

Tribe. Cassieae.

Miscellaneous. Illustrations: • D. procerum: Fl. Males. 12 (1996).

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.’.