Phragmidium tuberculatum  

Spermogonia epiphyllous in minute groups, 90-100 µm diam. and 20-40 µm high, honey-coloured. Spermatia 2.5-3.3 x ca 1·6 µm, ovoid.
Aecia on branches, petioles and nerves of the leaves in elongate pustules, on the leaves in smaller, rounded pustules, surrounded by clavate hyaline paraphyses. Aeciospores 20-30 x 18-24 µm, globose, subglobose or ellipsoidal, densely verrucose, hyaline, the wall rather thick with 6-8 scattered pores ca 4.5 µm diam. with membranes apparently hemispherical in optical section.
Uredinia hypophyllous, scattered or in groups, very small, pale to bright yellow, surrounded by inwardly curved clavate paraphyses to 60µm long and 6-18µm diam. Urediniospores 20-25 x 16-24 µm, globose, subglobose, ellipsoidal or ovoid, tuberculate, yellow, the wall ca 1.5 µm thick with 6-8 scattered pores 4-5 µm diam., the pore membrane in optical section hemispherical, intruding into the lumen of the spore.
Telia hypophyllous, scattered or in groups, small, black. Teliospores 55-110 x 30-36 µm, ellipsoidal-cylindrical to cylindrical, 4- to 6-celled, not constricted at the septa, the  base rounded, the uppermost cell longer than the rest, with a pale or hyaline apical papilla to 22 µm in length, abruptly passing into the apical spore membrane; verrucose, chestnut-brown, the wall 6-7 µm thick with 2-3 pores in each cell; pedicel hyaline, persistent, ± equal to the spore, base enlarged to 30 µm diam.

Description adapted from Wilson & Henderson (1966).