Abstract
Festuca devesae (Poaceae), a new species from the low mountains of northern Iberian Peninsula (Burgos and Álava provinces, Spain), is described. According to its morphology, it belongs to Festuca subsect. Festuca, the most diverse group within the genus. The new species differs from other known consectional taxa by having a continuous layer of abaxial subepidermal sclerenchyma in the leaf cross-sections, and by the leaf sheaths closed to the mouth. Both traits are found together only in F. segimonensis and F. hystrix, from which F. devesae clearly differs in the leaf apex shape, the size of the auricles, and the leaf anatomy in cross-section, among other traits. A detailed morphometric description, photographs, and data on leaf anatomy, phenology, ecology, and distribution are given. A comparison with morphologically similar species and an identification key are also provided.