Wall rue is native to
Europe and Britain and Ireland, eastern North America and parts of Asia, and is a fern which you can find in crevices on walls, as you can the true maidenhair and adder’s tongue. As a fern it is distantly related to adder’s tongue, common polypody, hart's tongue, bracken, common club moss, horsetail, moonwort, and all other ferns. It grows to around two or three inches high, and resembles maidenhair.
Like most ferns it has no flowers, but the spores can be seen on the underside of the leaves or fronds, being brown and then black when mature.
It is similar in colour to garden rue, which is perhaps why it gets its name. It was a specific for rickets in traditional medicine in
Britain, and was especially used for coughs in children and also for children’s ruptures.
In some parts of
Europe it was infused in milk to treat epilepsy, and a decoction of the fronds was given for kidney complaints. It was also used to staunch bleeding from minor wounds, as it has a fairly high tannin content.
Distilled water made from the fronds has been used as eye lotion for a variety of eye problems.
The fronds may be harvested in late spring and dried for later use, although it may not be possible to do this if the plant is listed as endangered or protected in your country.
The English herbalsit, Nicholas Culpeper, writing in the 17t century linked wall rue closely with maidenhair fern, and had this to say about the properties of each.
“The decoction of the herb Maiden-Hair being drank, helps those that are troubled with the cough, shortness of breath, the yellow jaundice, diseases of the spleen, stopping of urine, and helps exceedingly to break the stone in the kidneys, (in all which diseases the Wall Rue is also very effectual). It provokes women's courses, and stays both bleedings and fluxes of the stomach and belly, especially when the herb is dry; for being green, it loosens the belly, and voids choler and phlegm from the stomach and liver; it cleanses the lungs, and by rectifying the blood, causes a good colour to the whole body. The herb boiled in oil of Camomile, dissolves knots, allays swellings, and dries up moist ulcers. The lye made thereof is singularly good to cleanse the head from scurf, and from dry and running sores, stays the falling or shedding of the hair, and causes it to grow thick, fair, and well coloured; for which purpose some boil it in wine, putting some Smallage seed thereto, and afterwards some oil. The Wall Rue is as effectual as Maiden-Hair, in all diseases of the head, or falling and recovering of the hair again, and generally for all the aforementioned diseases. And besides, the powder of it taken in drink for forty days together, helps the burstings in children.”