Rust (fungus) only uredinia and telia. Spermagonia may be absent from each type but especially the microcyclic life cycle. In macrocyclic and demicyclic life cycles, the rust may be either host alternating (heteroecious), i.e., the aecial state is on one kind of plant but the telial state on a different and unrelated plant, or non-host alternating (autoecious), i.e., the aecial and telial states on the same kind of plant. Heteroecious rust fungi require two unrelated hosts to complete their life cycle, with the primary host being infected by aeciospores and the alternate host being infected with basidiospores. This can be contrasted with
Wheat yellow rust In 1953, Hylander et al. (1953) revived the name P. striiformis. "Yellow rust" takes its name from the appearance of yellow-colored stripes produced parallel along the venations of each leaf blade. These yellow stripes are actually characteristic of uredinia that produce yellow colored urediniospores. Primary hosts of yellow rust are "Triticum aestivum" (bread wheat), "Triticum turgidum" (durum wheat), triticale, and a few "Hordeum vulgare" (barley) cultivars. The alternate host was discovered by accident in 2010. Species of common barberry plants (the alternate host of wheat stem rust) were found harbouring stripe rust. When transferred to grass hosts, Kentucky Bluegrass was