Sophora
Sp. Pl. 1: 373. 1753.
Herbs, perennial, shrubs, or trees, unarmed. Stems erect, pubescent or glabrous. Leaves alternate, odd-pinnate; stipules usually present, caducous, linear to deltate; petiolate, petiole 5–30 mm; leaflets (7 or)9–23[–50], alternate or subopposite, stipels absent or minute and linear, blade margins entire, surfaces pubescent or glabrous (densely villous, sericeous, or glabrescent adaxially in S. tomentosa). Inflorescences 5–75[+]-flowered, terminal or axillary, racemes or panicles; bracts present, caducous; bracteoles caducous or absent. Flowers papilionaceous; calyx campanulate, lobes 5, subequal, acute to truncate, sometimes gibbous, adaxial lobes often connate in part; corolla white, creamy white, yellow, or purple, glabrous; keel usually connate in part; stamens 10, distinct or proximally connate; anthers dorsifixed; pistil linear to lanceolate. Fruits legumes, sessile or short-stipitate, narrowly oblong-moniliform, cylindric [compressed], fusiform, or torulose, dehiscent, pubescent [glabrous]. Seeds 1–15, light brown to mustard-yellow, globose to subglobose. x = 9.
Distribution
United States, Mexico, West Indies (Antilles, Bahamas), Central America, South America, Eurasia, Africa, Pacific Islands, Australia.
Discussion
Species ca. 50 (4 in the flora).
Sophora as traditionally circumscribed is recognized as an unnatural assemblage. Molecular studies have elucidated the relationships among taxa in Sophora in the broad sense, resulting in recognition of several smaller genera. In the flora area, Sophora, as currently circumscribed, comprises herbaceous plants arising from a woody root, and the woody species S. tomentosa. Two species in the flora area that formerly were included in Sophora are now included in Dermatophyllum (D. arizonicum and D. secundiflorum), as is the closely related Mexican species D. gypsophilum and two others are placed in Styphnolobium (S. affine and S. japonicum). Styphnolobium is distinct from Sophora (in the narrow sense) in molecular studies, falling into the Cladrastis clade; Dermatophyllum is in a separate lineage from the Cladrastis clade and outside a clade in which the North American taxa of Sophora (in the narrow sense) fall (J. J. Doyle et al. 1996; R. T. Pennington et al. 2001; M. F. Wojciechowski et al. 2004).
The seeds and foliage of some species of Sophora contain neurotoxic alkaloids. Although neurotoxicity has not been demonstrated in native Sophora species, G. E. Burrows and R. L. Tyrl (2013) discussed possible teratogenic effects.
Selected References
None.
Key
| 1 | Shrubs or small trees; corollas creamy white to yellow; coastal near beaches or in pinelands. | Sophora tomentosa |
| 1 | Herbs; corollas purple (fading blue), white, or creamy white; inland. | > 2 |
| 2 | Leaflet blades narrowly linear; leaf rachises 2–4 cm; corollas purple (fading blue). | Sophora stenophylla |
| 2 | Leaflet blades obovate to oblong or ovate to oblanceolate; leaf rachises (3–)5–17 cm; corollas white or creamy white. | > 3 |
| 3 | Inflorescences 7–15 cm; leaflet blades villous-tomentose abaxially, appressed- pubescent adaxially. | Sophora leachiana |
| 3 | Inflorescences 20–80 cm; leaflet blades sericeous abaxially, glabrous adaxially. | Sophora nuttalliana |