Genetic connectivity is crucial in rapidly changing environments as it allows exchange and dispersal of adaptive genes among plant populations. Matter et al. study patterns of historic gene flow, flowering phenology and contemporary pollen flow in two common herbs, Ranunculus bulbosus and Trifolium montanum, along an altitudinal gradient of 1200–1800 m a.s.l. among alpine meadows in Switzerland, a habitat type thought to be particularly sensitive to climate change. They determine that pollen-flow along the gradient is extensive, explaining the very low genetic differentiation along the mountain slope. Congruent with this finding, they find that despite the delay in flowering caused by altitude, the overlap in flowering periods is large enough to allow for extensive pollen dispersal between populations.