Strychnos is a genus of around 200 species of trees and woody lianas in the family Loganiaceae, order Gentianales. Native to the world's tropics, the genus has a pantropical distribution spanning Africa, Asia, Australia, and the Americas. All parts of many species — roots, stems, bark, and leaves — contain potent indole alkaloids, making Strychnos one of the most toxicologically significant plant genera in the world.
The most notorious member is Strychnos nux-vomica, the strychnine tree of tropical Asia, whose seeds yield the convulsant poison strychnine. Equally important historically is Strychnos toxifera of South America, one of the principal plant sources of curare, the arrow poison used by indigenous Amazonian peoples and later adopted in surgery as a muscle relaxant. Strychnos ignatii, the St. Ignatius bean of Asia, is closely related and similarly alkaloid-rich.
Not all species are purely toxic in their uses. In southern Africa, three species — S. cocculoides (suurklapper), S. spinosa (Natal orange), and S. pungens (black monkey orange) — are drought-tolerant trees whose ripe fruits are widely eaten and traditionally important. Strychnos potatorum, known as Therran or Nirmal in India, has long been used to purify water: its seeds act as a natural coagulant when rubbed against the walls of earthenware vessels.
Taxonomically, the genus is divided into 12 informal sections, though all sections except Spinosae are considered polyphyletic. The fossil record extends to the mid-Tertiary: remarkably well-preserved flowers of Strychnos electri were recovered from Dominican amber dated to between 15 and 45 million years ago.
Etymology
The name strychnos was used by Pliny the Elder in his Natural History as a name for Solanum nigrum. It derives from the Ancient Greek στρύχνον (strúkhnon), meaning "acrid" or "bitter". In ancient Greek usage the word was not restricted to a single plant but applied loosely to several species sharing the quality of toxicity.
Distribution
Strychnos has a pantropical distribution, with species occurring across tropical Africa, Asia, Australia, and the Americas. The genus is especially diverse in sub-Saharan Africa and tropical South America.
Cultural Uses
Indigenous peoples of Amazonia have long prepared curare — a muscle-paralyzing arrow poison — from the bark and stems of Strychnos toxifera and related species. In southern Africa, the fleshy fruits of S. cocculoides, S. spinosa, and S. pungens (collectively called "monkey oranges") are eaten fresh and used in traditional foods and beverages. In India, the seeds of S. potatorum (Nirmal) have been used for centuries to clarify turbid water, acting as a natural coagulant.
History
Two exceptionally preserved fossil flowers attributed to Strychnos electri were discovered in amber from the Dominican Republic, in resin of the extinct tropical tree Hymenaea protera. The amber is dated to approximately 15–45 million years ago (mid-Tertiary), providing some of the earliest direct evidence of this genus in the fossil record.
Taxonomy Notes
The genus is currently divided into 12 sections: Strychnos, Rouhamon, Breviflorae, Penicillatae, Aculeatae, Spinosae, Brevitubae, Lanigerae, Phaeotrichae, Densiflorae, Dolichantae, and Schyphostrychnos. Phylogenetic analyses have shown that all sections except Spinosae are polyphyletic, meaning the informal sectional classification does not reflect the evolutionary history of the genus.
