This is another version of the common Maiden Hair fern that grows in the woods here. I've heard it called Southern Maiden Hair. It is a native American fern, but a version of it also grows in Europe where it has been used as a medicinal plant. It is only native as far north as Virginia, but grows happily here in a sheltered spot. It has a perference for lime soils, shade and moisture.
Both the Latin and English names are revealing. Adiantum means unmoistuened or water-repelling, and Venus is said to have arisen from her watery home with dry hair. Because of this connection with hair, the plant has been used as a hair tonic, but it seems to have little value for this purpose.
Herbal references indicate that it has long been known as an emmenagogue, but even more generally as an expectorant because of its mucilaginous properties. The plant, fronds and rootstocks alike, is dried and mixed with boiling water and taken as needed. Pretty vague directions, but that seems typical for these medicinal plants. I guess people just knew what to do with them and didn't feel the need to include lots of written directions.
The French have a cough remedy known as Sirop de Capillaire, made by using 5 ounces of the dried plant and 2 ounces of peeled licorice root in 3 pints of boiling water, adding, after 6 hours, 3 pounds of sugar and 1 pint of orange juice for palatability.
I was afraid to try this plant originally since it looked to delicate and wasn't rated for this zone, but it has increased to a rather large clump. It grows about a foot tall and grows here under a Japanese maple in a bed with heucheras, hostas and other ferns.