Strychnine is an alkaloid that is naturally present in the seeds of Strychnos nux-vomica and Strychnos ignatii plants. These plants belong to the Loganiaceae family. Strychnine is most commonly associated with Strychnos nux-vomica, which is native to Southeast Asia. The seeds of Strychnos nux-vomica contain strychnine and other related alkaloids and have been historically used in traditional medicine. It's worth noting that strychnine is a highly toxic compound and should be handled with extreme caution.