I don't know anything about this plant or its effects on users, but that aside the importation of just a few "seeds" from non-native plants can cause unintended environmental problems for the future.

An example in this area might be the Tamarisk, which has a beautiful flower, which in some locations has almost replaced the native willows and made large areas less useable for both man & wildlife.

I think we need to be very cautious on the importation of non-native plants for their habitat as well as possible undesirable uses. The latter could turn out to be the minor problem.

Khat is a stimulant drug with effects similar to cocaine.