Definitions

1. noun

A small, disk-shaped structure formed by a fungus, such as a rust, to attach itself to a plant

“The fungus developed appressoria on the leaves of the infected plant, allowing it to absorb nutrients.”

2. noun

A specialized organ formed by some fungi, such as Uredinales and Ustilaginales, to attach to and penetrate plant tissues

“The appressoria of the fungus Ustilago maydis form on the surface of maize leaves.”