Cat’s-Ear (Hypochæris radicata L.). No record of poisoning of Cat’s Ear has been found, but it may be mentioned here, since Ewart says of it: “It contains a bitter, milky sap, which makes it unpalatable though not entirely poisonous.... An exclusive diet of this weed could not help but injure stock eventually.”
Dodders (Cuscuta sp.), when parasitic on clovers and fed as fodder or hay, have been suspected of causing digestive troubles in horses and cattle in the United States. Müller records a case of poisoning of young pigs by C. europæa, with inflammation of the intestines and nervous symptoms. Barbey determined the presence of the glucoside Cuscutin in C. Epithymum.
Viper’s Bugloss (Echium vulgare L.) is suspected of being poisonous; according to Friedberger and Fröhner it causes slavering (see also Cynoglossum).
Hound’s Tongue (Cynoglossum officinale L.). To what extent this plant is actually poisonous is not clear, but with some other members of the order (Echium vulgare, Anchusa officinalis), it contains the two alkaloids Consolidine and Cynoglossine—the former of which paralyses the central nervous system and the latter the peripheral nerves. (Greimer, 1900: vide Henry).
According to Hooker, Hound’s Tongue is narcotic and astringent, and Smith includes it as a simple vegetable irritant, causing nausea and purging. No records of actual poisoning of animals have been found.
Broom-rape (Orobanche minor Sutt.) has been suspected, and according to Boitel is liable to cause violent colic when it occurs in considerable proportion in clover and is ingested with it (73). On the other hand, in a case noted by Stapledon, in which Broom-rape (O. minor) had completely overrun the aftermath on a farm near Fishguard, two-year-old cattle devoured the plant with apparent relish and cleared off most of it in a few days after being turned in. The farmer stated that he saw no trace of colic or other ill effects. (Jour. Bd. Agric., September, 1916.)
Great Mullein (Verbascum Thapsus L.). Though it does not appear to be touched by farm live-stock the Great Mullein must be mentioned here. The leaves and flowers have been used medicinally as an emollient and pectoral, while the seeds possess narcotic properties and serve to stupefy fish (73). Pammel states that the plant causes irritation, but is probably not very poisonous to stock.
Toadflax (Linaria vulgaris Mill.). Cornevin describes Toadflax as acrid and poisonous, but says that stock reject it, and he could record no accidents to animals. In his full and excellent account of this weed, Kraus says it is regarded as poisonous, or suspected of being so, but that according to most accounts it is not harmful to cattle (168). Leunis regards it as suspicious on account of its acridity. Some German authorities say it is willingly eaten by cattle, but it is generally believed to be avoided, and owing to its disagreeable odour and acrid taste this view is probably correct. The plant has not been exhaustively studied, and while Smith gives the toxic principle as Oil of Snapdragon and the resin Gratiolin, it may be observed that Toadflax contains the glucoside Linarin (C64H56O40).
Figworts (Scrophularia nodosa L. and S. aquatica L.). These plants are not likely to be eaten by animals, but Cornevin states that the former is strongly emetic and purgative, and that in excess it may cause superpurgation ending in death. Müller says that the two species have respectively caused poisonous symptoms in a cow and a sheep; in the case of the cow there were loss of appetite and symptoms of paralysis. From S. nodosa Walz extracted a bitter, crystalline substance, Scrophularine.
Yellow Rattle (Rhinanthus Crista-galli L.). When grass land is put under the plough Yellow Rattle present may re-appear in a cereal crop as a semi-parasite, and its seeds may later be ground up with the grain, imparting a reddish or violet-brown colour and an unpleasant taste to the flour and even bread made from it. It is strongly suspected of being poisonous, like Pedicularis and Melampyrum, but it is by no means clear how far it may prove harmful to stock. It is believed by some people to impart a bad taste to the butter made from the milk of cows grazing on infested pastures. Lehmann ate without harm 35 grammes (about 1¼ oz.) of the seeds made into a cake and cooked; and during four days he gave a rabbit 1238 grammes (2·7 lb.) of the fresh plant with half-ripe seeds, without apparent injury (73).