Prunus padus
Taphrina padi is a fungal plant pathogen that induces the form of pocket plum gall that occurs on bird cherry ("Prunus padus"). The gall is a chemically induced distortion of the fruits, which are swollen, hollow, curved and greatly elongated, without a seed or stone, but retaining the style. The twigs on infected plants may also be deformed with small strap-shaped leaves.