Family Tree of Asplenium javorkeanum and his son Asplenium ceterach with the shape of their fronds. Drawing taken from the excellent article "Phylogenetic analysis of Asplenium subgenus Ceterach (Pteridophyta: Aspleniaceae) based on plastid and nuclear ribosomal DNA ITS sequences.". http://www.amjbot.org/cgi/content/full/90/3/481
This tetraploidy allowed to leave their ancestral habitat and conquer new lands, to confer greater resistance to drought, sun exposure and limestone soil alkalinity, can live in many different habitats and soils, from sea level to the mountain peaks, reaching its expansion in the Canary Islands to the west, the Middle East to the East, Germany, Benelux and the British Isles to the north and the Mediterranean coast of Africa to South.
The fronds of the doradilla have a length ranging between 3 and 20 cm, the petiole is brown-black and much smaller than the blade, which is lanceolate or ovate-lanceolate, with the beam of a green color varies greatly habitat, from bright green to dark green and dull, even with bluish-gray tinge. The underside is covered with paleas shiny, silvery iron. The sori are oblong-linear with or without a rudimentary indusium. The pinnae are alternate, 6 to 15 pairs, ovate or oblong with rounded apex and entire or crenate edge.
of a typical sheet of Ceterach officinarum ssp. officinarum.
Underside of a sheet with paleaceous hairs and conspicuous sori, formed by sporangia like dark balls, which are about to disperse the spores.