uredinium
/jʊˈriːdɪniəm/
noun
- A small, powdery pustule on a plant caused by rust fungi, which produces spores.
- Each uredinium releases thousands of spores that can infect nearby plants.
- Gardeners often spot a uredinium as a raised, rusty-colored spot on the stem.
- The underside of the leaf was covered with orange uredinia.