Cercis
Sp. Pl. 1: 374. 1753.
Trees or shrubs, unarmed. Stems gray or gray-brown to red-brown, twigs dark red-brown, erect, hairy or glabrous. Leaves alternate, 2-ranked, unifoliolate; stipules present, caducous, ovate, membranous; petiolate, petiole glabrous or hairy; pulvinate proximally and distally; blade margins entire, surfaces glabrous or hairy. Inflorescences cauliflorous or from short shoots on wood one year or older, fasciculate; bracts present, caducous. Flowers pseudopapilionaceous, appearing before leaves, banner enclosed by wings, wings enclosed by keel petals; calyx slightly zygomorphic, enlarged adaxially, persistent, lobes 5, connate, magenta, rounded to broadly triangular; corolla: petals 5, free, clawed, usually pink, rarely white, [magenta], inserted on floral cup; keel locked abaxially by folds in each petal forming a pocket; stamens 10, distinct, enclosed in keel pocket; filaments hairy proximally, inserted on floral cup; anthers versatile, 2-locular, dehiscing by longitudinal slits; ovary laterally compressed, short stalked; style tapering to a narrow tube, stigma triangular, terminal. Fruits legumes, sessile or short-stipitate, brown to red-brown or dark magenta, compressed laterally, lanceolate, narrowly winged on prominently veined abaxial suture, dull or glossy, indehiscent or dehiscent, if dehiscent, opening on one or both margins, glabrous or sparsely hairy. Seeds 3–7, red-brown, laterally compressed, with circular hilum, funicular aril lobes absent, orbicular. x = 7.
Distribution
North America, n Mexico, e, s Europe, Asia.
Discussion
Species 10 (3 in the flora).
Cercis is found in mesic to arid habitats in North America and Eurasia. North American Cercis appears to have diverged from western Eurasian Cercis in the middle Miocene (P. A. Fritsch and B. C. Cruz 2012). Cercis spokanensis Knowlton is a fossil taxon from the Pacific Northwest.
In spite of the inclusion of Cercis in floras of New Mexico (I. Tidestrom and T. Kittell 1941; W. C. Martin and C. R. Hutchins 1980; K. W. Allred and R. D. Ivey 2012), no specimens of Cercis outside cultivation in that state could be located.
Selected References
None.
Lower Taxa
Key
| 1 | Leaf blades coriaceous, leaves thickened (0.15–0.3 mm thick), margins distinctly sinuate, surfaces dull to glossy adaxially, glabrous or hairy abaxially and adaxially; arid regions of Oklahoma, Texas. | Cercis canadensis |
| 1 | Leaf blades thin, leaves (0.05–0.25 mm thick) to subcoriaceous, margins flat, surfaces usually dull (sometimes slightly reflective but not glossy), glabrous or hairy abaxially, glabrous adaxially; s Canada, c, e, w United States (including Oklahoma and Texas). | > 2 |
| 2 | Leaf blade apex usually obtuse to acuminate, sometimes retuse; adaxial surface dull, abaxial surface glabrous or hairy, often much lighter in color; calyx 5–6.8 mm wide; s Canada, c, e United States. | Cercis canadensis |
| 2 | Leaf blade apex emarginate to retuse, adaxial surface dull or slightly reflective, abaxial surface glabrous or hairy, both surfaces nearly concolor; calyx 6.4–10 mm wide; w United States. | > 3 |
| 3 | Calyx 6.4–9.2 mm wide; banner 3.4–5.3 mm wide, wings 4.7–6.5 mm, keel. | > 5 |
| 5 | 8–7.5 mm wide; California, Oregon. | Cercis occidentalis |
| 3 | Calyx 8.4–10 mm wide; banner 4.9–6.3 mm wide, wings 7.2–9 mm, keel. | > 7 |
| 7 | 2–8.9 mm wide; Intermountain region of Arizona, Nevada, Utah. | Cercis orbiculata |