This plant is seldom known by any other name than common brake or bracken, sometimes modified to lady-bracken, fern-brake, or hog-brake.
Photo - F. Fyles.
The bracken is a coarse fern with a creeping, woody, almost black rootstock. The stalk of the frond or leaf is from one to three feet high, and the blade measures from one to three feet across by two to four feet in length. The stalk, with maturity, becomes straw-coloured, or brownish, stiff, stout, ridged, swollen at the base. The blade is dull green, the general outline triangular, the widely spreading branches twice pinnate. In the spring the young leaves are bent over at the top and curled in. The oblong obtuse lobes are strongly outlined by the reflexed margin which forms, in this case, a second indusium or covering to the spore-cases. As the spore-cases develop, they push aside the outer indusium and, fitted close together in several rows, they form quite a distinct golden-brown margin to the underside of each lobe. The spores, or reproductive bodies, are ready for dissemination from July to September. The spore-cases open with a snap, and the spores, light and easily carried by the wind, are scattered far and wide. When they reach the moist earth they germinate, but the germinated spores do not produce a true fern-plant. They give rise to another stage of its life, a small flat, green body (pro-thallus). On the underside of the prothallus are tiny organs whose union results in the development of a true fern-plant, which in its turn produces spores and thus completes the life cycle.
Common in thickets, on hillsides, and in sandy soil from the Atlantic to the Pacific.
The toxic principles of bracken have not yet been fully investigated, but it has been shown by experiment that the action of the poison is cumulative.
The experiments carried on by Hadwen in British Columbia (1917) proved that the ingestion of dried bracken was the cause of a disease among horses known as "staggers." He says: "During the hard winter of 1915-16 the mortality amongst horses in the Fraser valley and on Vancouver Island was very heavy. As an extreme instance we cite the following: 'In the little village of St. Elmo, B.C., out of twenty-four horses owned by eleven farmers, sixteen died of bracken poisoning, four recovered, and the balance (four) did not take the disease.' The horses attacked are usually those that receive the minimum amount of care, but well-cared-for, greedy horses may contract the disease through eating their bedding, which often consists of bracken which has been left in their mangers." Hadwen also reports the poisoning of two horses from eating green bracken in a pasture where other vegetation was scarce. One of the horses died. Chesnut and Wilcox (1901) state that "Cases of poisoning of horses and cattle by this plant have been reported from England and from a few localities in the United States." Pott also refers to the poisoning of cattle by eating bracken in quantity. Stockman (1917) experimented with a bull-calf by feeding it freshly cut bracken for a period of twenty-nine days. The calf was found dead on the thirtieth day.
The first general signs of poisoning as given by Hadwen are, an unsteady gait, good appetite, animal inclined to constipation, eye congested, flanks tucked up, nervousness. In the later stages if the head is raised the horse may fall. It stands with the legs spread, and has a distinctly intoxicated look. Greedy horses are most liable to attack.
Mueller, in reference to fatal poisoning among horses, gives the symptoms as timidity, slower movement or action, loss of balance, dilated pupils, reddening followed by yellowing of the conjunctivae, and slowing of the pulse.
Remedy and Means of Control: In all cases of poisoning, professional advice should be obtained. The treatment recommended by Hadwen to the farmer who is unable to obtain such aid is as follows: First remove all ferny hay and bedding. Give a quart of raw linseed oil, taking especial care that none falls into the lungs. Give good clean hay, warm bran mashes, and roots. The horse should be kept as quiet as possible, owing to its nervous excitability. Warmth is of aid in combatting the affection, whilst a cold, draughty stable tends to lower the vitality.
Ploughing and manuring is one of the best methods of exterminating bracken. The deep-lying rootstocks will not all be destroyed the first year, but after two or three years of thorough cultivation, very few if any will be found.
On steep hillsides and pastures where tillage would be out of the question, cutting the green tops off will in time starve the rootstocks, particularly if a good dressing of lime is applied to the soil immediately after the cutting. The lime serves as a check to the bracken and also as an encouragement to the growth of grasses. In regard to the best time for cutting, Thomas Tusser wrote in 1557: "In June and in August, as well doth appeere Is best to mowe Brakes of all times of the yeere."