Urediniospore

Urediniospores are the thinner-walled spores of some fungi: (rusts and smuts), from which the basidium arises.

Development
Urediniospores develop in the uredium at the bottom of a leaf's surface.

Morphology

 * Urediniospores are usually consist of two dikaryote nuclei within one constricted cell resembling the number 8 without a septation. As the spores germinate, the nuclei undergo karyogamy and thereafter meiosis, giving rise to four-celled basidia with haploid basidiospores.


 * They don't have a thick-capped telia as compared to teliospores.


 * Looks like a balloon pinched in the middle, (like an 8 without septation)