The alkaloids of two Amazonian species of Tabernaemontana have been studied; each species yielded indole alkaloids of only one structural type. Thus, T. riedelii contained the new alkaloids (+)-8-oxominovincine and (+)-minovincine, as well as a mixture of (±)- and (+)-vincadifformine. T. rigida contained (±)-vmcamine, (+)-vincamine, (+)-apovincamine, and a substance believed to be a mixture of (±)- and (—)-14-epivincamine. © 1968, American Chemical Society. All rights reserved.