Puccinia sessilis  

Spermogonia epigenous or hypogenous amongst the aecia, reddish-yellow to brown.
Aecia hypogenous, loosely clustered or sometimes circinate, in rounded groups on circular or irregular large yellow spots, cup-shaped with a laciniate white recurved peridium, peridial cells firmly connected, not in distinct rows, with the punctate outer wall strongly thickened, to 8-10 µm thick and the inner wall to 3-5 µm, with small warts. Aeciospores 18-27 µm diam., globose or ellipsoidal, yellowish, the wall thin, very finely verruculose.
Uredinia amphigenous, scattered, minute, punctiform or shortly linear, soon naked, pulverulent, yellowish-brown, without paraphyses. Urediniospores 20-28 x 18-24 µm, globose to ellipsoidal, brownish yellow, the wall distantly echinulate, with about 7 scattered pores.
Telia similar to the uredinia, sometimes confluent, long covered by the epidermis, pulvinate, black. Teliospores 35-52 x 15-22 µm, cylindrical to cylindric-clavate, rounded or truncate and darker above, hardly constricted, somewhat narrowed below, brown, the wall smooth, to 5µm thick at the apex, the pedicel short, brown, usually deciduous.