The Rusty-back fern, Ceterach officinarum, has rusty scales on the backs of its leaves. These cover the spore-producing sori and probably help prevent the fern from drying out. During dry spells the fronds roll in at the edges.
Growing to just few inches, this fern is found in dry crevices in limestone and in old mortared walls. A small colony grows on a north-east facing sandstone wall on Station Road, Ossett.
It is best grown in a cold frame, potted rather high, among loam mixed with a large proportion of brick-rubbish, and not over-watered.
Thomas More, British Ferns, 1861
Rusty-back fern is a member of the spleenwort family and was used to treat diseases of the spleen. Legend has it that Cretan sheep with spleen disorders would greedily devour its rootstock.
It’s scientific name Ceterach is said to derive from the Arabic ‘Cheterak’ the name that Eastern physicians used for this plant.