Urediospore-derived infection structures of Phakopsora apoda, a rust fungus on kikuyu grass (Pennisetum clandestinum), penetrate the host leaf directly through the cuticle and not through the stomata. A urediospore germinates on the leaf to form a short germ tube which is delimited from a terminal appressorium by a septum. Most appressoria form at the junctions between epidermal cells. Appressoria are often sessile to the urediospores. From the base of the appressorium, a penetration peg develops, which penetrates through the host cuticle and epidermal cell wall. Penetration of the epidermal cell wall occurs approx. 6 h post inoculation. Once inside the epidermal cell, the penetration peg expands to form a penetration hypha, which traverses the epidermal cell and emerges into the intercellular space of the mesophyll tissue. A septum is formed in the intercellular portion of the penetration hypha, delimiting a primary hypha which extends further into the mesophyll, before branching to form two secondary hyphae. This penetration process appears to be very similar to that of Phakopsora pachyrhizi on soybean.