The hyphae composing the mycelium are provided with haustoria which project into the cells of the affected part (fig.
Appressoria are also formed by some parasitic fungi, as a minute flattening of the tip of a very short branch (Erysiphe), or the swollen end of any hypha which comes in contact with the surface of the host (Piptocephalis, Syncephalis), haustoria piercing in each case the cell-wall below.
A and B, mycelium (m), the mix t ure over the affe c ted with haustoria (h).
They form a superficial mycelium on the surface of the plant, the hyphae not usually penetrating the tissues but merely sending haustoria into the epidermal cells.
Synalissa, Micarea, the haustoria pierce the membrane, but do not penetrate the protoplasm (fig.
Mycelium with haustoria (h); 2, Erysiphe; A and B, mycelium (m), with haustoria (h).