A genus of about eighty species of trees, shrubs, subshrubs and perennial herbs, scattered over the world. Leaves odd-pinnate, usually with numerous leaflets. Flowers in racemes or panicles, sometimes solitary. Corolla composed of standard, wings and keel, but not obviously of the pea-flower shape in S. tetraptera and its allies. Stamens free or almost so. Ovary stalked. Pods constricted between the seeds, hence necklace-shaped (moniliform), usually fleshy or woody and indehiscent. The cultivated species fall into two well-marked groups, the first represented by S. japonica, whose flowers are pea-shaped (papilionaceous) and the second by S. tetraptera and its allies (the Edwardsia group), in which the papilionaceous form of the corolla is obscured owing to the petals pointing forward. The latter group has a remarkable distribution: Lord Howe Island; New Zealand and Chatham Island; Hawaii; Easter Island; Juan Fernandez Islands; temperate S. America; Réunion (in the Mascarene group of islands). Thus the group is predominantly insular in distribution and only in New Zealand and Chile is it found more than a few miles from the ocean. See further in: Good, Geography of Flowering Plants (1953), p. 117 and fig. 34).
The generic name Sophora was originally applied by Linnaeus to S. alopecuroides, an herbaceous perennial mainly of W. Asia but extending into S.E. Russia and the Crimea, sophora or sophera being, according to him, an ‘ancient’ name for some similar plant. It is in fact an Arab name, probably for the plant that Linnaeus later named Cassia sophera. The rendering Sophora for the present genus allowed him to make a pun. For he remarked that the name could also signify ‘of the wise men’ (sophorum), since it brought ‘knowledge and warning’ that plants which combine papilionaceous flowers with free stamens, as in Sophora, could not be regarded as forming a distinct class (Hort. Cliff. (1737). p. 156). Because of its ten free stamens and single pistil he placed Sophora in his Decandria Monogynia, where it is associated with many genera quite unrelated to the Leguminosae, among them Rhododendron. The majority of pea-flowered genera of the Leguminosae have all the ten stamens, or nine of them, more or less connate, and those known to Linnaeus were placed in his Diadelphia Decandria.