Two adjacent populations ofP. lanceolatawere observed to have different rosette morphologies and apparently, capacities for vegetative reproduction. Plants growing in an open, sunny habitat were clumped while those found growing in a periodically shaded habitat, only developed as single rosettes. Representative genotypes from each population were cloned from leaf cuttings and propagated in controlled‐environment facilities. Growth and vegetative reproduction were measured under two contrasting irradiances to determine whether the differences seen in the field were primarily genetic or environmentally induced. These studies indicated that each population was adapted to the light regime most similar to that prevailing in its natural habitat. The clumping in the open population was the result of a greater capacity for vegetative reproduction.