| # The genera of Leguminosae-Caesalpinioideae and Swartzieae |

L. Watson and M.J. Dallwitz

### Cercis L.

Circis Chapman, Siliquastrum Adans.

Type species: C. siliquastrum L.

Habit and leaf form. Trees, or shrubs; unarmed.

Phyllotaxy spiral. The leaves ostensibly simple, or two-lobed; palmately veined. Stipules absent or early caducous or very inconspicuous in mature leaves; membranous.

Inflorescence and floral morphology. The inflorescences on older branches; unbranched; short, fascicle-like simple racemes. The flowers not distichous. Bracteoles present; small, not enclosing the flower buds; absent at anthesis, or persistent beyond anthesis (rarely).

The flowers hermaphrodite; pentamerous; coloured. Floral tube length relative to total hypanthium + calyx length about 0.25. Hypanthium present; asymmetrically saucer-shaped to cupular. Calyx 5 (shortly, broadly 5-toothed); not covering the rest of the flower in bud; gamosepalous; markedly irregular; members not imbricate. Corolla present; very irregular (the abaxial member larger than the rest); 5; polypetalous. Petals clawed, or clawed and sessile; imbricate; imbricate-ascending; red. Disk present and conspicuous. The androecium comprising 10 members; members all free of one another; members all more or less equal in length (but the members declinate); comprising only fertile stamens. Fertile stamens 10. Anthers attached at the base of the connective, or attached well above the base of the connective; dehiscing longitudinally. Ovary stipitate; free. Stigma not dilated (or only very inconspicuously so, the style filiform). Ovules numerous.

Fruit, seed and seedling. Fruit a two-valved pod (flat, thin); straight; without markedly twisting or enrolling valves; winged longitudinally; narrowly 1 winged; not becoming woody. The mature valves with conspicuous, prominent, raised venation, or without prominent venation; conspicuous venation if present, oblique or reticulate, not predominantly longitudinal. Seeds endospermic; not arillate (the hilum circular); with a straight or slightly oblique radicle; amyloid-negative. Cotyledons flat; of Type 2; epigeal.

Transverse section of lamina. Druses common in 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. Hooked hairs not seen. Cassieae-type leaf pseudo-glands not seen. Expanded and embedded hair-feet absent. Basally bent hairs absent. Adaxial: Adaxial interveinal epidermal cell walls straight in optical section; thick. Stomata adaxially very rare. Abaxial: Abaxial stomata not predominantly paracytic (anomocytic). Abaxial epidermis not papillate. Abaxial interveinal epidermal cell walls straight, or gently undulating; not conspicuously pitted in optical section; scarcely staining with safranin; thin.

Wood anatomy. Wood with septate fibres; storied.

Cytology. Basic chromosome number, x = 7. 2n = 14.

Species number and distribution. 9 species, or 10 species. North temperate.

Tribe. Cercideae.

Comments. Widely cultivated.

Miscellaneous. Illustrations: • Cercis siliquastrum: Bot. Mag. 27 (1808). • C. siliquastrum: Baillon, Histoire des Plantes 2 (1870). • Cercis siliquastrum: Nat. Pflanzenfam. III (1894). • Cercis chinensis and C. glabra: 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: 4th August 2019. delta-intkey.com’.

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