Kengia serotina (synonyms: Cleistogenes serotina, Festuca serotina) is a species of grass in the Poaceae family, native to Europe and temperate Asia. Culms are geniculately ascending, 1 mm in diameter, and 30–60 cm in height. Leaf-blades are spreading, flat, or involute, from 4–8 cm long and 3–5 mm wide.