Strychnos is a genus of flowering plants, belonging to family Loganiaceae (sometimes Strychnaceae). The genus includes about 190 species of trees and lianas, distributed around the world's tropics.
- The Strychnine tree, Strychnos nux-vomica, native to tropical Asia, is the source of the poison strychnine.
- Strychnos ignatia ("St. Ignatius bean"), is a closely related Asian shrub/tree.
- The species Strychnos toxifera is one of the 2 plant sources of the poison curare.
- Three trees from Southern Africa, commonly known as "monkey oranges", are drought-tolerant and produce popular edible fruits: the corky-barked monkey orange or suurklapper, Strychnos cocculoides, the Natal orange or green or spiny monkey orange, Strychnos spinosa, and the black or spiny-leaved monkey orange Strychnos pungens.
- The ripe seeds of Strychnos potatorum,, known as Therran or Nirmal, can be ground and used as a coagulant to purify water; or they may be rubbed against the inside walls of the earthenware water containers.