Carex agastachys is the Eastern parallel species of the Western Carex pendula s.str., the crossover between the two species runs through Germany. Carex agastachys shown here has red margins of the ligules and obovate nutlets (widest near one end) in the fruits, while Carex pendula s.str. has white margins of the ligules and elliptical nutlets (widest in the middle). The also generally stated difference that the peduncles of the female spikes of Carex agastachys shall be significantly rougher than those of Carex pendula s.str., I can't confirm for C. agastachys from the Ungeheuerklamm South of Bruchsal and C. pendula s.str. from Weinheim, Hemsbach, and Schriesheim (all in the Northern Upper Rhine valley), they are pretty rough in both cases. Perhaps this attribute is more different if comparing geographically more distant populations. Both species are not only native wild plants, but also cultivated as ornamental plants, and running wild from there, too.