Rusts are fungal plant pathogens of the order Pucciniales causing plant fungal diseases.
Rust (fungus)
Germinating urediniospore of Puccinia graminis, model from the late 19th century, Botanical Museum Greifswald
Rust hypha attacking stoma (1600x magnification)
Rust fungus on a leaf, under low magnification.
Galls or cecidia are a kind of swelling growth on the external tissues of plants. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or warts in animals. They can be caused by various parasites, from viruses, fungi and bacteria, to other plants, insects and mites. Plant galls are often highly organized structures so that the cause of the gall can often be determined without the actual agent being identified. This applies particularly to insect and mite plant galls. The study of plant galls is known as cecidology.
Oak artichoke gall caused by Andricus foecundatrix
Artichoke gall cut open to reveal wasp larva
Knopper gall caused by Andricus quercuscalicis
Oak gall caused by Neuroterus albipes forma laeviusculus