Desert Broom Rust Fungus
Uredinales
This bright yellow-orange fungal parasite is erupting from a stem of Desert Broom, Baccharis sarothroides (Asteraceae). Obsserved along Devil's Canyon east of Superior, Arizona, USA.
Many kinds of fungi live in association with plants in the Sonoran Desert. The associations can range from something akin to a disease whereby the plant's energy and fitness is sapped by the fungus, to symbiosis that benefits both plant and fungus. The shrub that hosted the fungus shown here appeared to be less robust than uninfected desert broom plants nearby. Further, careful investigation might reveal, however, that the plant gets something from the fungus that improves its survival.
Tentative identification of this fungus was provided by Dr Marcin Piątek, Polish Academy of Sciences, Krakow, Poland.