Occurrence of Festuca apennina De Not. (4 × Fape), F. pratensis Huds. (2 × Fp) and the triploid, sterile hybrid F. apennina × F. pratensis (3 × Fape × Fp) was studied in 12 regions of the Swiss Alps. In total, 1908 plants were sampled in elevational strata scaled by 50 m between 850 and 2000 m a.s.l., and accompanying vegetation was assessed for each sampling point. The hybrid 3 × Fape × Fp was more frequent and more dominant than both parental species around 1400 m, and had a wider elevational distribution than 2 × Fp and 4 × Fape, which were confined to lower and higher elevation, respectively. As evidenced by their preferred accompanying species, 2 × Fp colonizes dryer, nutrient poorer environments than 4 × Fape which clearly prefers wet and nutrient rich environments. On the contrary, 3 × Fape × Fp thrives similarly well in both environments. The ability to reach an important biomass proportion in a sward, and the wide environmental adaptation of 3 × Fape × Fp is favored by its capacity to strongly expand by rhizomes. A single genotype of 3 × Fape × Fp was found to colonize an entire field of 2.3 ha with a maximum distance between clonal plants of 304 m. It is concluded that 3 × Fape × Fp is a potentially valuable pasture plant for use at higher altitudes, but it may reduce biodiversity via suppressing less competitive plant species.
