The Garden Snail, Helix aspersa, has a thin, lightweight shell but that still looks cumbersome as it explores a fern-filled crevice in an old wall (see previous posts). As I drew it from a photograph that I’d taken this morning I noticed traces of damage to the shell with what appears to be a healed break in the rim and hairline fracture on the ‘back’ of its shell.
I imagine it being surprised, perhaps by a bird, retracting into its shell then falling from the wall onto the pavement below.
A second snail clung precariously to the base of the stems of Common Ragwort, growing from a crevice near the top of the six foot high wall amongst the fronds of Rusty-back Fern and Wall Rue.
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.