directed speciation A speciational trend recognized in plants: the species do not conform to a continuum of adaptive types, but rather to a stepwise succession of distinct species. The evolutionary significance of such a trend is unclear. It may relate to differential survival as opposed to differential speciation along an environmental gradient, i.e. to directional species selection rather than directed speciation.

directed speciation A speciational trend recognized in plants: the species do not conform to a continuum of adaptive types, but rather to a stepwise succession of distinct species. The evolutionary significance of such a trend is unclear. It may relate to differential survival as opposed to differential speciation along an environmental gradient, i.e. to species selection rather than directed speciation.