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The genera of Leguminosae-Caesalpinioideae & Swartzieae

L. Watson and M.J. Dallwitz

Zenia Chun

Type species: Z. insignis Chun.

Habit and leaf form. Tall trees; unarmed.

The leaves compound; pinnate; imparipinnate. The leaflets many per leaf (about 18–25); alternate; petiolulate; ovate-lanceolate, entire, symmetrical or nearly so; pinnately veined, with a predominant ‘midrib’. Stipules absent or early caducous or very inconspicuous in mature leaves; membranous. Stipels absent.

Inflorescence and floral morphology. The inflorescences long-peduncled terminal; branched; (dubiously) of cymose units; panicles. Bracteoles present.

The flowers hermaphrodite; actinomorphic to slightly irregular; not ‘papilionaceous’; pentamerous (rarely), or not pentamerous throughout; departing from pentamery usually in the androecium; coloured. Hypanthium absent, the androecium hypogynous. The perianth comprising distinct calyx and corolla. Calyx 5; covering the rest of the flower in bud; polysepalous; markedly irregular (the fifth sepal much smaller); members imbricate. Corolla present; slightly irregular (the petals slightly unequal); 5; without greatly reduced members; polypetalous. Petals shortly clawed; keeled, exceeding the sepals, imbricate; imbricate-descending with the posterior petal (vexillum) outside; red. Disk present and conspicuous. The androecium comprising 5 members; not declinate; members all free of one another; members all more or less equal in length, or markedly unequal (usually with one member at least somewhat shorter); including staminodia, or comprising only fertile stamens. The staminodia if present, 1 (the short member being sometimes reduced and filiform). Fertile stamens 4–5 (usually 4, depending on the constitution of the shorter member). Anthers attached at the base of the connective (longer than filaments); dehiscing longitudinally. Ovary hairy, shortly stipitate; free. Stigma subterminal on the short style, not dilated. Ovules few, or numerous (up to about 9).

Fruit, seed and seedling. Fruit indehiscent; not drupaceous; curved (falcate); narrowly winged longitudinally (along adaxial suture); elliptic-oblong, compressed, membranous, not becoming woody. The mature valves with conspicuous, prominent, raised venation to without prominent venation; conspicuous venation reticulate, not predominantly longitudinal. Seeds with a straight or slightly oblique radicle.

Species number and distribution. 1 species (Z. insignis). South China, Thailand.

Tribe. Cassieae.

Miscellaneous. Illustrations: • Z. insignis: li shu gang (2005).

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.’.