Climate change seems to be skewing the sex ratios of an alpine herb towards male plants.

William Petry at the University of California, Irvine, and his colleagues analysed data on populations of the herb valerian (Valeriana edulis) in the Rocky Mountains of Colorado as the region became warmer and drier over the past few decades. They found that in 2011, plants at the highest elevations were only 23% male, whereas at lower altitudes, where the climate is warmer and wetter, the plants were up to 50% male. Across 9 populations at a variety of elevations, there was an average of 6% more males in 2011 than in 1978.

A higher male-to-female ratio could result in increased pollination — and therefore seed production — which could help the plants to expand their range as they adapt to climate change, the authors suggest.

Science 353, 69–71 (2016)