Silver Weed (Potentilla Anserina L.). This well-known and elegant little weed is scarcely likely to be eaten to any extent by farm stock, though it may possibly be taken occasionally on roadsides. It has not been proved to be poisonous, but Pott states that it has a strongly constipating effect (213).
Tormentil (Potentilla Tormentilla L.). In relation to supposed bracken poisoning (see p. [87]) in regard to which experiments were conducted by the Board of Agriculture and Fisheries, Tormentil occurred in several instances with the bracken in localities where this plant was reported to cause poisoning. Two feeding experiments in which the weed was fed to heifers gave negative results. In a further case, however, 4 or 5 lb. were collected from a field where sick animals were grazing, and fed to a heifer; it appeared to be the cause of rise of temperature (to 106° F.), diarrhœa, and the passing of a considerable quantity of blood in the fæces for three days, after which the animal improved. It was, however, slaughtered, and lesions were found similar to those found in animals dying in the field from so-called bracken poisoning. Though the plant was suspected, results generally were not held to prove that it was the cause of poisoning (25). According to Van Rijn the root of Tormentil contains a considerable quantity of Chinovic acid (C32H48O6?).
Wall-Pepper (Sedum acre L.) is regarded as emetic and purgative, but to lose the harmful properties on drying.
Sundews (Drosera sp.) are reputed to be poisonous to sheep, but no evidence has been found.
White-Rot or Marsh Penny-Wort (Hydrocotyle vulgaris L.) is stated to have caused inflammation of the digestive tract, and hæmaturia; and to contain a toxic substance Vellarin (213).
Wild Parsnip (Pastinaca sativa L.). This plant has often been supposed to be poisonous, but Pammel shows that in Iowa the plant is quite harmless, as it appears to be in Britain.
Devil’s-Bit (Scabiosa succisa L.) is stated by Moir to have caused injury to cattle in one instance (Vet. Record, 1899), causing salivation, gritting of the teeth, twitching of facial muscles, and slightly protruded, abraded, swollen and sensitive tongue. An experiment on cattle showed the plant to induce violent inflammation of the mouth and tongue.
All-Heal (Valeriana officinalis L.) is not likely to be eaten by stock in sufficient quantity to cause poisonous symptoms, though it is stated to contain the poisonous Valerianic acid and Oil of Valerian. According to Chevalier (vide Henry) this plant contains an alkaloid not yet fully characterised.
Canadian Erigeron (Erigeron canadensis L.), sporadic in England, is suspected in America. It contains an oil, chiefly a terpene (C10H16). It has an acrid taste, causes smarting of the eyes, soreness of throat, aching of extremities, and colic; and irritation to people handling it (203).
Mayweeds (Anthemis sp.). It is not at all clear whether these plants are more than irritant in character, and they are so very common and widely distributed that there would probably be more evidence if they were poisonous. A. Cotula is regarded as suspected by Smith and Halsted, while Ewart says that it is obnoxious to stock on account of its unpleasant flavour, and if eaten by them in time of scarcity is apt to give their flesh, milk, or butter an unpleasant flavour. Güssow states that this species blisters the mouth and nostrils of animals. In his investigations at Kew, Greshoff found that the seeds of A. Cotula and A. arvensis contain much hydrocyanic acid. (He further found that the cyanogenetic glucoside from A. aetnensis Schouw. and A. chia L. belongs to the amygdalin type, giving off hydrocyanic acid and benzaldehyde on hydrolysis. “The strong odour of benzaldehyde may even be observed on grinding the seeds with water. Species of Anthemis contained from 0·15 down to 0·03 per cent. of hydrocyanic acid.”)