Rust (fungus) fungi may be able to infect two different plant hosts in different stages of its life cycle, and may produce up to five morphologically and cytologically distinct spore-producing structures viz., spermogonia, aecia, uredinia, telia, and basidia in successive stages of reproduction. Each spore type is very host specific, and can typically infect only one kind of plant. Rust fungi are obligate plant pathogens that only infect living plants. Infections begin when a spore lands on the plant surface, germinates, and invades its host. Infection is limited to plant parts such as leaves, petioles, tender shoots, stem, fruits, etc. Plants with
Stem rust studied the stem rust. Thirty years later it received its name, "Puccinia graminis", by Persoon, and in 1854 brothers Louis René and Charles Tulasne discovered the characteristic five-spore stage that is known to some stem rust species. The brothers were also able to make a connection between the red (urediniospore) and black (teliospore) spores as different stages within the same organism, but the rest of the stages remained unknown. Anton de Bary later conducted experiments to observe the beliefs of the European farmers regarding the relationship between the rust and barberry plants, and after successful attempts to connect the basidiospores