As nouns the difference between shrub and iboga
is that
shrub is a woody plant smaller than a tree, and usually with several stems from the same base or
shrub can be a liquor composed of vegetable acid, fruit juice (especially lemon), sugar, sometimes vinegar, and a small amount of spirit as a preservative modern
shrub is usually non-alcoholic, but in earlier times it was often mixed with a substantial amount of spirit such as brandy or rum, thus making it a liqueur while
iboga is (
taxlink), a perennial rainforest shrub and a source of the hallucinogen ibogaine.
As a verb shrub
is (obsolete) to lop; to prune.