Asplenium petrarchae is a tiny fern

Fern

A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...

 of the family Aspleniaceae

Aspleniaceae

The Aspleniaceae is a family of ferns, included in the order Polypodiales or in some classifications as the only family in the order Aspleniales....

. Its fronds are densely pubescent-glandular with length between 5 and 14 cm. Petiole

Petiole (botany)

In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...

 less than the sheet of dark brown and shiny. Sores along the central line of the pinnae, subelliptical and confluent when mature. It sporulates almost throughout the year.

Habitat

It lives among the stones of the walls of the terraces and in crevices of limestone rocks. It loves the light and supports a few hours of sunshine in the early hours and tangential final hours of the day. It hates the rain directly on its fronds, preferring the moisture comes to its roots through the soil soaked by seepage of rainwater. For this usually grow well inside the crevices of the rocks and between the stones of the walls of the terraces, where no rain falls over. Although well-supported long periods of drought, the driest months and hot summer enters in estivation

Estivation

Aestivation is a state of animal dormancy, characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions...

( summer sleep ), dehydrated their fronds, to appear dead. With the first rains of autumn will rehydrate the dried fronds and it will green quickly.

Subspecies

It has two subspecies: one diploid, which is actually the original fern, Asplenium petrarchae ssp. bivalens with a chromosome number of 2n = 72 and one autotetraploid by spontaneous doubling of their genome, Asplenium petrarchae ssp. petrarchae, very more abundant than the subspecies bivalens. Its genomic dotation is 2n = 144 chromosomes.