Puccinia phragmitis  

Spermogonia amphigenous, in groups, 80-90 µm diam., subepidermal, globose, whitish to yellow-brown.
Aecia hypogenous, on circular red or deep purple spots, 0.5-1.5 cm diam., in dense clusters, shortly cylindrical or cup-shaped, with a !aciniate, white, recurved margin, the spore mass white. Aeciospores 16-26 µm diam., verruculose, nearly hyaline.
Uredinia amphigenous, scattered or ± gregarious, elliptical or linear, sometimes confluent, rather large, convex, pulverulent, brown, without paraphyses. Urediniospores 25-35 µm diam., subglobose or obovoid, brownish, the contents hyaline, the wall 3-4 µm thick, verruculose, with four equatorial pores.
Telia numerous, similar but larger and thicker, very convex and compact, black. Teliospores 45-65 x 16-25 µm,  ± cylindrical, rounded at both ends or with the apex somewhat attenuated, constricted at the septum, deep yellowish-brown, wall 2-3 µm thick at the sides, paler and thicker (4-7 µm) above, smooth or sometimes with very fine granulations; pore of upper cell apical, of lower close to the septum; pedicels 100-200 µm long, hyaline or yellowish, thick, persistent.