Order IV. Filices, Juss.—Ferns.
Character.—Herbaceous plants with a perennial rhizome, more rarely having an erect arborescent trunk [when they are called tree ferns, filices arboreae; Fig. 195]; trunk coated, of a prosenchymatous structure, with the entire cylinder of woody fasciculi divided into two concentric parts, the one narrow, placed between the bark and the wood; the other larger, central, medullary, sending fasciculi of vessels towards the petioles, and communicating with the exterior by means of chinks in the woody cylinder. Leaves [frondes] scattered upon the rhizome or rosaceo-fasciculate on the apex of the caudex, with circinate vernation, annual or perennial, the base of the petioles persistent, growing to the caudex; simple or pinnate, entire or pinnatifid, [equal-] veined (the veins composed of elongated cells), frequently having cuticular stomata. Sporangia [thecae], placed on the veins of the back or margin of the leaves, collected in little naked heaps [sori], or covered with a membranous scale [indusium], or transmuted margin of the leaf, pedicellate [with the stalk (seta), passing round them in the form of an elastic ring (annulus)], or sessile, unilocular, indefinitely dehiscent. Sporet [sporules] numerous, free, globose, or angular, in germination at first elongated in every direction, throwing out radicles downwards, and the cauliculus upward (Endlicher).
Properties. The leaves are mucilaginous, and frequently slightly astringent and aromatic. The rhizomes contain starch, saccharine matter and gum, usually tannic and gallic acids, with more or less bitter matter, and sometimes both fixed and volatile oils, resin. They are considered to possess astringent and tonic properties, and in some cases act as vermifuges.
From the tuberous rhizomes of fern is obtained, in some of the Polynesian islands, as well as in some other parts of the world, a farinaceous or ligneous matter, which is employed by the natives as a nutritive substance. The rhizomes are cooked by baking or roasting. In general, however, they are only resorted to in times of scarcity, when other and more palatable food cannot be obtained [Ellis, Polynesian Researches, vol. i. p. 363; Bennet. Narrative of a Whaling Voyage, vol. ii. p. 394, 1840.—Dieffenbach (Travels in New Zealand, vol. ii. 1843) says that the "korau or mamake, the pulpous stem of a tree-fern (Cyathea medullaris) is an excellent vegetable;" and, he adds, "it is prepared by being cooked a whole night in a native oven."].
Several ferns have been used in medicine. Those which I shall particularly notice are Nephrodium Filix mas, still retained in the British pharmacopoeias, and used as a vermifuge, and Adiantum or Maidenhair, a syrup of which, or a substitute for it, is still found in the shops under the name of capillaire.
Ruiz [Memoria sobre la legitima Calaguala y otras dos raices que con el mismo nombre nos vienen de la America Meridional, Madrid, 1805. A translation of Ruiz' Memoir is contained in Lambert's Illustration of the Genus Cinchona, p. 98, 182.] has written a memoir on three fern roots sent from Peru, in South America, to Spain, under the name of Calaguala (more correctly Ccallahuala, from ccallua, a batten or trowel, and hualas, a boy, i. e. a boy's batten). The first, or the genuine Calaguala, or Ccallahuala, or slender Calaguala, is the rhizome of Polypodium Calaguala, Ruiz; the second, called thick Calaguala, Puntu-puntu, and sometimes Deer's tongue (Lengua de Ciervo), is the rhizome of Polypodium crassifolium, Linn.; and the third, termed middling Calaguala, the little cord (Cordoncillo), or Huacsaro, is the rhizome of Acrostichum Huacsaro, Ruiz. The first is the species which should be used in medicine: as, however, it is unknown in English commerce, I need not describe it. Professor Guibourt [Hist. Nat. des Drogues simpl. t. ii. p. 87, 4me. ed. 1849.] has figured three sorts of the rhizome, but states that, judging from Ruiz's description, he has not seen the true Calaguala. He once found the Maltese fungus (Cynomorium coccineum) in some Calaguala which he received from Marseilles. Calaguala has been analyzed by Vauquelin [Ann. Chimie, t. lv. p. 22.]. This rhizome is regarded in Peru as possessing deobstruent, sudorific, diuretic, anti-venereal, and febrifuge virtues; and it is frequently used to thin the blood, to promote perspiration, and to mitigate rheumatic and venereal pains. It is commonly administered in the form of decoction, prepared by boiling one ounce of the fresh root in six pints of water to three pints. This decoction is taken ad libitum as a kind of diet drink.