As is alpine plants, mountain plants would also be vulnerable to extinction as a result of global warming if they differentiate along altitudes in reality with each ecotype having narrow distribution range. Here, I introduce several case studies of mountain herbaceous plant species displaying neutral genetic or adaptive floral trait differentiation. First, the floral size of some species like Campanula punctata and Prunella vulgaris differs along altitude and is adapted to altitudinally variable pollinator assembledges. Second, species like Cimicifuga simplex is composed of several genetically differentiated ecotypes that are distributed parapatrically or allopatrically along altitudinal gradients. To meet the challenges posed by future climate warming, it is essential to clarify the genetic and ecological differentiation of mountain plants along altitude.