Mitragyna javanica is a cousin to the more commonly known mitragyna speciosa or Kratom. Although it appears to have the same effects as M. speciosa, it is weaker in effects when the same dosage is taken. There is a difference in the chemical constituents, as M. javanica does not contain the constituent mitragynine, but contains a high amount of another alkaloid called mitrajavine.
M. javanica is a rare plant and is more difficult to find, and it does look similar to its cousin, though its leaves completely different.
M. speciosa, many are experimenting with Mitragyna javanica in order to achieve similar effects of Kratom, though there is very little research done with the javanica species.