Spermogonia and aecia not known.
Sori forming urediniospores and teliospores from the same structures, erumpent from the host stems; rather large, elongate, dehiscing with longitudinal splits, often confluent, pulverulent, chestnut brown. Urediniospores 22-34 µm diam., globose to ellipsoidal, mid brown, the wall 3-5 µm thick, verrucose-echinulate when young, becoming nearly smooth when mature. Teliospores 35-46 x 19-28 µm, ellipsoidal to ± cylindrical, truncate at the apex and base. slightly constricted at the ± central septum, mid brown, the wall smooth, 3-4 µm thick, slightly thicker at the apex, the pedicel to 50 µm long, flexuous, slender, hyaline, often inserted obliquely, deciduous.
Not formally assessed for Great Britain, listed as Data Deficient for Wales.
In living stems of Juncus acutus, possibly also on J. maritimus.
Reported from VC15 E. Kent, VC4 N Devon, VC41 Glamorgan, VC44 Carmarthen, VC46 Cardigan and VC48 Merioneth; also from the Channel Is.