Taxonomic key

1. Trees or shrubs in the Rio Balsas Depression and Tehuacan-Cuicatlan Valley, Mexico ....................................................................2

- Shrubs or small trees from the North and Bajio regions of Mexico ...................................................................................................3

2. Tree; leaflets glabrescent on the adaxial surface, pilose to pubescent on the abaxial surface, ovate-elliptic, 2.5—5.6× 1.5—2.5 cm; legume 7.3–12.6 × 2.8–4.4 cm, oblong-elliptic, margin hirtule, 1—5 seeded; tropical deciduous forest in Guerrero and Michoacan, Mexico ................................................................................................................................................................................ C. lewisiae

- Shrub; leaflets tomentulose, orbicular, 0.9–2.6 × 0.9–1.5 cm; legume 3.7–7.2 × 1.9-3.2 cm, oblong-elliptic, tomentulose, 2–3 seeded; in deciduous tropical forest in the Tehuacan-Cuicatlan Valley (Puebla and Oaxaca) ........................... C. rosalindamedinae

3. Shrubs or small trees; leaflets densely pubescent below, obovate, 1.7–8.5 × 1.2–4.5 cm; legume 5–7 × 2.5–3 cm, oblong to elliptic, mucronate, densely pubescent on both surfaces, 1–3-seeded; in dry forest and bushland, in Hidalgo, Queretaro, San Luis Potosi, Tamaulipas and Guanajuato, Mexico (Bajio and Northwest of Mexico).......................................................................... C. pringlei

- Tree; leaflets glabrous, oblong-lanceolate, 3–6 × 1.5–3 cm; legume 7–14 × 3–4 cm, oblong, glabrous, 2-3 seeded; in low rocky bluffs in dry seasonal forest (Colima and Jalisco)................................................................................................................ C. glabra