Pythium debaryanum

— Shows hypha growing toward the potato cell wall.

— Shows hypha attached to wall and about to penetrate.

Note the black line at the point where the hypha penetrates the wall.

It is known as a plant pathogen on many kinds of wild and cultivated plants, including peanut, beet, eucalyptus, tobacco, and pine trees.

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Photographs enlarged from portions of a motion photomicrograph, showing the method of cell wall penetration by Pythium hyphae.
A. — Shows the hypha growing against the potato cell wall. Sufficient pressure has already been applied to cause the hypha to bend. Notice that this bending increases in later photographs.
B. — A little later stage than A.
C. — The tip has broken through as a small tube
D. — Penetration is complete. Notice the constriction of the hypha at the point where it penetrates the potato cell wall.