Aecia: unknown in GBI material.
Uredinia: hypophyllous, in roundish to irregular clusters 1-3 mm across, often confluent, powdery, bright yellow, sometimes mixed with telia. Urediniospores (17-) 19-21 (-23) x (14-) 16-18.5 (-19.5) µm, ovoid to ellipsoidal or subglobose, the wall thin (ca 1.5 µm thick, measurements in water), finely echinulate, the spines ca I µm in height; pores several, inconspicuous; the pedicel thick-walled, ± cylindrical, rarely remaining attached.
Telia: very small, hypophyllous, waxy in appearance. Teliospores 22-29 x 13-15 µm (measured in warmed lactic acid), the length/breadth ratio rather variable, ± clavate, 2-celled, not or hardly constricted at the septum, hyaline to pale yellow, smooth, thin-walled.
Not formally assessed but the host is introduced and the fungus presumably also.
On living leaves of cultivated Oxalis sp.
Widespread in southern England, more local further north, as far as Edinburgh and Islay. Common in Ireland.