The word ceterach comes from an Arabic word applied to the plant by Persian physicians
Rhizome: erect, branching, scales clathrate.
Frond: 15 cm high by 2 cm wide, evergreen, monomorphic, blade/stipe ratio: 8:1.
Stipe: green, from base all up the rachis, scaly, vascular bundles: 2 C-shaped, back to back, uniting to 1 upwards to an X-shape.
Blade: pinnatifid, lanceolate, leathery, deep green upper surface, scales dense, light brown, entirely covering the lower surface.
Pinnae: 6 to 12 pair, alternate; margins entire or sometimes irregularly crenate, slightly bending upwards, revealing the scales; veins netted, veins closing near the margins, not visible without removing the scales.
Sori: linear, along veins, indusium: vestigial, replaced by scales, sporangia: dark brown, maturity: late summer, then overwintering to maturity early .
Dimensionality: a rosette, fairly flat on the ground.
Habitat: on limestone substrates.
Distribution: maritime and southern Europe, northern Africa, east to the Himalayas.
Hardy to -25°C, USDA Zone 5.
The densely scaly lower surface and the pinnatifid form make this unique. Demands a site with excellent drainage, and can withstand drying out in the manner of some polypodies.
Ceterach officinarum DC.