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The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Leucostegane Prain

Type species: L. latistipulata Prain.

Habit and leaf form. Trees; unarmed.

Phyllotaxy spiral. The leaves compound; pinnate; paripinnate. The leaflets opposite or sub-opposite; petiolulate; with markedly twisted petiolules; markedly asymmetrical to symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’; without a continuous marginal nerve. Stipules present, persistent and conspicuous in mature leaves; large, leafy; intrapetiolar, basally connate. Stipels present.

Inflorescence and floral morphology. The inflorescences on the older wood; branched; of racemose units; fascicles (of small racemes). The flowers not distichous. Bracteoles present; small, not enclosing the flower buds; persistent beyond anthesis; not valvate; free.

The flowers hermaphrodite; not pentamerous throughout; departing from pentamery in the corolla and in the androecium, or in the calyx, in the corolla, and in the androecium. Floral tube length relative to total hypanthium + calyx length about 0.25. Hypanthium present; infundibuliform, the tube fleshy. The perianth comprising distinct calyx and corolla. Calyx present (exceeding the ccorolla); 4; covering the rest of the flower in bud; polysepalous (the lobes obtuse, reflexing); members imbricate. Corolla present; very irregular; 2, or 3 (with two petals located between the upper and lateral calyx lobes, and an adaxial one if present staminode-like); including greatly reduced members, or without greatly reduced members; polypetalous. The androecium comprising 4 members; members all free of one another; members markedly unequal; including staminodia. The staminodia 2; short, between and adaxial to the fertile stamens. Fertile stamens 2 (located opposite the lateral sepals, with their long filaments decurved and folded in the bud). Ovary exserted, stipitate; eccentric, with the stipe adnate (the style filiform, circinate in bud). Stigma oblique.

Fruit, seed and seedling. Fruit a two-valved pod; oblong, compressed, apiculate, becoming woody. Seeds with a straight or slightly oblique radicle.

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 exhibiting fibres or sclereids which are unaligned with the vascular bundles. 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 markedly sinuous in high-focus optical section; conspicuously pitted; thick. 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; thick.

Species number and distribution. 2 species (L. grandis and L. latistipulata). Malay Peninsula, Borneo.

Tribe. Detarieae.

Miscellaneous. Illustrations: • L. grandis and L. latistipulata: 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: 22nd March 2017.’.