Plants Poisonous to Live Stock

by Harold Cecil Long

Buttercups (Ranunculus sp.). A number of species of Ranunculus are acrid, irritant or severely poisonous, as the case may be. There are variations in the poisonous character according to the season, and some parts of the plant are more toxic than others. At the time the young shoots develop in the spring but little of the poisonous principle is present, and some (e.g. R. Ficaria) are not then poisonous, but a larger quantity of the poisonous principle forms later, and some species are especially dangerous at the time of flowering, after which the toxicity decreases with the maturity and state of dryness of the plant. The flowers are the most poisonous, and then the leaves and stem. It does not seem to have been demonstrated that the seeds of any species are dangerous, though Henslow states that the fruits of some species, when green, appear to be most intensely acrid.

Some species of Ranunculus are especially harmful (R. sceleratus, R. Flammula, and R. bulbosus), while others are less so (R. lingua, R. Ficaria, R. acris). The toxic principle is volatile, and buttercups are easily rendered innocuous by drying or boiling—so much so that when dried in hay they may be regarded as a nourishing food for stock, and are readily eaten. Indeed, R. repens is scarcely, if at all, injurious even when green, though a case of fatal poisoning to sheep said to be due to this species was reported in the Veterinarian in 1844. Fresh R. aquatilis is held to be quite harmless, and has been used as a fodder. “Along the banks of the Hampshire Avon, and other places in the same neighbourhood, it is used by the peasantry as fodder. They collect it in boats and give it to their cows and horses, allowing the former about twenty to thirty pounds a day. One man is said to have kept five cows and a horse, with little other food but what they could pick up on the heath, using no hay but when the river was frozen. Hogs eat it and will live upon it alone until put up to fatten.” (Johnson and Sowerby—Useful Plants of Great Britain.)

R. sceleratus L., or Celery-leaved Buttercup, is probably the most toxic species, and it is stated that in man a single flower may cause poisonous symptoms resembling those due to Anemone and Colchicum. It is considered especially dangerous to cattle, and has caused many losses: among its French names are Mort aux Vaches, and Herbe sardonique. Poor people have been known to eat the young shoots when boiled, heat dispelling the poison.

R. Flammula L., the Lesser Spearwort, has repeatedly proved fatal to horses and cattle.

R. bulbosus L., the Bulbous Buttercup, is somewhat variable in toxicity, and is least dangerous after the flowers have dropped their corolla, and the bulb-like rootstock is most harmful in autumn and winter. The flowers are the most dangerous part.

R. Ficaria L., Lesser Celandine, varies in toxicity with locality and season, being most harmful at the flowering period. It is stated that wood-pigeons eat the roots with avidity, and that the young shoots have been eaten as a salad in Germany, as they are not toxic. An English veterinary surgeon (Flower) recorded that three heifers were poisoned by it (Vide Cornevin).

R. acris L., Acrid Buttercup or Tall Crowfoot, is a frequent cause of poisoning in cattle, and Cornevin says it is perhaps the species which causes the most accidents.

Toxic Principle. The buttercups contain an acrid and bitter juice, the chemical properties and composition of which are not well known, but it is believed that the substance is identical with the Anemonin of the Anemone sp. (q.v.). Beckurts isolated Anemonin and Anemonic acid from R. acer. Pott, however, states that the poisonous species contain the two alkaloids Aconitine and Delphinine.

Symptoms. The buttercups are acrid, burning and narcotic, causing irritation of the mucous membrane, with inflammation of the intestinal tract.

Cornevin shows that R. sceleratus induces gastro-enteritis, colic, diarrhœa with excretion of black foul-smelling fæces, vomiting when possible, falling-off in milk yield in cows, nervous symptoms, reduction in pulse, and stertorous respiration, dilation of the pupils, enfeebled condition, difficult mastication, spasmodic movements of the ears, lips, etc.,—followed in serious cases by convulsions, sinking of the eye in its socket, possibly stoppage, and death in 6 to 12 hours after convulsions first appeared.