Appressorium

It is a flattened, hyphal "pressing" organ, from which a minute infection peg grows and enters the host, using turgor pressure capable of punching through even Mylar.

Turgor pressure increases inside the appressorium and a penetration hypha emerges at the pore, which is driven through the plant cuticle into the underlying epidermal cells.

[8] In response to surface signals, the germ tube tip undergoes a cell differentiation process to form a specialized infection structure, the appressorium.

(1883), in 'Ueber einige neue und weniger bekannte Pflanzenkrankheiten', coined the name "appressorium" for the adhesion body formed by the bean pathogen Gloeosporium lindemuthianum on the host surface.

[12] Appressoria are induced in response to physical cues including surface hardness and hydrophobicity, as well as chemical signals of aldehydes[13] exogenous cAMP, ethylene, the host's ripening hormone and the plant cutin monomer hexadecanoic acid.