Melampsora euphorbiae  

Spermogonia subepidermal, flattened to hemispherical, orange.
Aecia on leaves amphigenous, to ca 500 µm diam. and on stems elongate, to ca 4 mm in length, orange, peridium absent, lacking paraphyses. Aeciospores 21-28 x 19-24 µm, globose to ellipsoidal, the wall 1.5-2 µm thick, densely verrucose.
Uredinia usually hypogenous on leaves, rarely on stems, to ca 500 µm diam., pulvinate, bright yellowish, pulverulent. Paraphyses 40-60 µm tall, the apex clavate to globose, 14-16 µm diam., the wall 1.5-2 µm thick. Urediniospores (21-) 24-27 x (16-) 17.5-20.5 (15-22 x 12-20 µm fide Wilson & Henderson 1966), broadly ellipsoidal, ovoid or obovoid, the contents yellow, the wall 2.5-3.5 µm thick (1.5-2 µm fide Wilson & Henderson 1966), densely echinulate, hyaline, apparently without germ pores.
Telia rarely present, amphigenous and on stems, subepidermal, minute, often confluent and elongate on stems, at first reddish brown and then dark brown to black. Teliospores in a single palisade, 18-60 x 7-15 µm, cylindrical, sometimes angular in horizontal section due to compression from surrounding spores, rounded to truncate at both ends, reddish brown to chestnut brown, the wall 1.5-3 µm thick, smooth, without germ pores.