About Asplenium petrarchae (Guérin) DC.
Asplenium petrarchae (Guérin) DC. is a small fern species that belongs to the Aspleniaceae family. Its fronds are densely covered in glandular hairs, and grow to between 5 and 14 cm (2.0 to 5.5 inches) in length. The petiole is shorter than the leaf blade, and it is dark brown and shiny. Sori grow along the central vein of each pinna; they are subelliptical in shape and become confluent when they reach maturity. This fern produces spores for most of the year. It grows among the stones of terrace walls and in the crevices of limestone rocks. It prefers bright conditions, and tolerates a few hours of direct sunlight during the early morning and late afternoon. It dislikes direct rain falling on its fronds, and instead prefers that moisture reach its roots through soil that has been soaked by rainwater seepage. For this reason, it typically grows well inside rock crevices and between terrace wall stones, locations where direct rain does not hit its fronds. Although it can tolerate long periods of drought, it enters estivation (summer dormancy) during the hot, driest summer months. During this time, its fronds dehydrate and can appear completely dead. Once the first autumn rains arrive, the dried fronds rehydrate and quickly turn green again.
