Only some few of our native Ferns are known to possess medicinal virtues, though they may all be happily pronounced devoid of poisonous or deleterious properties. As curative simples, a brief consideration will be given here to the common male and female Ferns, the Royal Fern, the Hart's Tongue, the Maidenhair, the common Polypody, the Spleenwort, and the Wall Rue. Generically, the term "fern" has been referred to the word "feather," because of the pinnate leaves, or to farr, a bullock, from the use of the plants as litter for cattle. Ferns are termed Filices, from the Latin word filum, a thread, because of their filamentary fronds. Each of those now particularized owes its respective usefulness chiefly to its tannin; while the few more specially endowed with healing powers yield also a peculiar chemical acid "filicic," which is fatal to worms. In an old charter, A.D. 855, the [183] right of pasturage on the common Ferns was called "fearnleswe," or Pascua procorum, the pasturage of swine (from fearrh, a pig). Matthiolus when writing of the ferns, male and female, says, Utriusque radice sues pinguescunt. In some parts of England Ferns at large are known as "Devil's brushes"; and to bite off close to the ground the first Fern which appears in the Spring, is said, in Cornwall, to cure toothache, and to prevent its return during the remainder of the year.
The common Male Fern (Filix mas) or Shield Fern, grows abundantly in all parts of Great Britain, and has been known from the times of Theophrastus and Dioscorides, as a specific remedy for intestinal worms, particularly the tape worm. For medicinal purposes, the green part of the rhizome is kept and dried; this is then powdered, and its oleo-resin is extracted by ether. The green fixed oil thus obtained; which is poisonous to worms, consists of the glycerides of filocylic and filosmylic acids, with tannin, starch, gum, and sugar. The English oil of Male Fern is more reliable than that which is imported from the Continent. Twenty drops made into an emulsion with mucilage should be given every half-hour on an empty stomach, until sixty or eighty drops have been taken. It is imprudent to administer the full quantity in a single dose. The treatment should be thus pursued when the vigour of the parasite has been first reduced by a low diet for a couple of days, and is lying within the intestines free from alimentary matter; a purgative being said to assist the action of the plant, though it is, independently, quite efficacious. The knowledge of this remedy had become lost, until it was repurchased for fifteen thousand francs, in 1775, by the French king, under the advice of his principal physicians, from Madame Nouffer, [184] a surgeon's widow in Switzerland, who employed it as a secret mode of cure with infallible success. Her method consisted in giving from one to three drams of the powdered root, after using a clyster, and following the dose up with a purge of scammony and calomel. The rhizome should not be used medicinally if more than a year old. A medicinal tincture (H.) is now prepared from the root-stock with proof spirit, in the autumn when the fronds are dying.
The young shoots and curled leaves of the Male Fern, which is distinguished by having one main rib, are sometimes eaten like asparagus; whilst the fronds make an excellent litter for horses and cattle. The seed of this and some other species of Fern is so minute (one frond producing more than a million) as not to be visible to the naked eye. Hence, on the doctrine of signatures, the plant—like the ring of Gyges, found in a brazen horse—has been thought to confer invisibility. Thus Shakespeare says, Henry IV., Act II., Scene 1, "We have the receipt of Fern seed; we walk invisible."
Bracken or Brakes, which grows more freely than any other of the Fern tribe throughout England, is the Filix foemina, or common Female Fern. The fronds of this are branched, whilst the male plant having only one main rib, is more powerful as an astringent, and antiseptic; "the powder thereof freely beaten healeth the galled necks of oxen and other cattell." Bracken is also named botanically, Pteris aquilina, because the figure which appears in its succulent stem when cut obliquely across at the base, has been thought to resemble a spread eagle; and, therefore, Linnaeus termed the Fern Aquilina. Some call it, for the same reason, "King Charles in the oak tree"; and in Scotland the symbol is said to be an impression of the Devil's foot. [185] Again, witches are reputed to detest this Fern, since it bears on its cut root the Greek letter X, which is the initial of Christos.
In Ireland it is called the Fern of God, because of the belief that if the stem be cut into three sections, on the first of these will be seen the letter G; on the second O; and on the third D.
An old popular proverb says about this Bracken:—
"When the Fern is as high as a spoon
You may sleep an hour at noon,
When the Fern is as high as a ladle
You may sleep as long as you're able,
When the Fern is looking red
Milk is good with faire brown bread."
The Bracken grows almost exclusively on waste places and uncultivated ground; or, as Horace testified in Roman days, Neglectis urenda filix innascitur agris. It contains much potash; and its ashes were formerly employed in the manufacture of soap. The young tops of the plant are boiled in Hampshire for hogs' food, and the peculiar flavour of Hampshire bacon has been attributed to this custom. The root affords much starch, and is used medicinally. "For thigh aches" [sciatica], says an old writer, "smoke the legs thoroughly with Fern braken."
During the Seventeenth Century it was customary to set growing Brakes on fire with the belief that this would produce rain. A like custom of "firing the Bracken" still prevails to-day on the Devonshire moors. By an official letter the Earl of Pembroke admonished the High Sheriff of Stafford to forbear the burning of Ferns during a visit of Charles I., as "His Majesty desired that the country and himself may enjoy fair weather as long as he should remain in those parts."
In northern climates a coarse kind of bread is made [186] from the roots of the Brake Fern; whilst in the south the young shoots are often sold in bundles as a salad. (Some writers give the name of Lady Fern, not to the Bracken, but to the Asplenium filix foemina, because of its delicate and graceful foliage.) The Bracken has branched riblets, and is more viscid, mucilaginous, and diuretic, than the Male Fern.