A species complex which cannot be reliably identified from aecial material. Wilson & Henderson (1966) list numerous varieties which have since been reduced with some attaining species status. Uredinia and/or telia are required for a precise identification which are restricted to Carex pendula

References: 
Wilson, M. & Henderson, D.M. (2011 reprint) British Rust Fungi
Termorshuizen, A.J. & Swertz, C.A. (2011) Dutch Rust Fungi