In addition to the foregoing, there is good authority for saying that the following plants may impart a disagreeable flavour to milk, and in many cases the butter made from it:—

Anthemis arvensisL.(Corn Chamomile).
Anthemis CotulaL.(Stinking Mayweed).
Artemisia Absinthium L.(Wormwood).
Conium maculatum L.(Hemlock).
Hyoscyamus niger L.(Henbane).
Matricaria Chamomilla L.(Wild Chamomile).
Pinguicula vulgaris L.(Butterwort).
Senebiera didyma Pers.(Lesser Wartcress).
Sium angustifolium L.(Lesser Sium).
Sium latifolium L.(Water Parsnip).
Tanacetum vulgare L.(Tansy).
Thlaspi arvense L.(Penny Cress).

(See also Index “Milk, plants affecting,” p. [117].)

PLANTS WHICH CAUSE MECHANICAL INJURY.

There are a number of plants which, while not necessarily physiological poisons, may induce injuries of a severe character when taken by animals, and by causing festering may bring about septic poisoning. For example the sharp pointed fruits of Stipa pinnata and Nardus stricta may cause injury to the skin and mouth, piercing the palate and causing inflammation, and when eaten may even perforate the wall of the intestine and cause death; and the awned glumes of species of Bromus or the spikelets of Hordeum may injure the gums, causing inflammation, ulceration, sores, the formation of pus, and loss of teeth. The Bromus and Hordeum, also, together with over-matured “heads” of Trifolium incarnatum, may give rise to Phytobezoars or balls in the stomach of horses and cattle (60, 119). The sharp pointed fruits of Erodium cicutarium may cause local irritation by working into the wool of sheep. Aira caespitosa may also cause injury to the mouth of stock.

A case is recorded in New South Wales in which cattle and horses ate Shepherd’s Purse (Capsella Bursa-pastoris). The cattle were unaffected, but the horses scoured, though most of them soon recovered when removed from the cultivated paddock containing the weed. Two young horses, however, showed signs of colic, became bloated, and died. It was then found that they contained balls of fibrous material (one weighed 1 lb. 9½ oz.) which consisted to the extent of nearly 50 per cent. of fibres from Shepherd’s Purse, and death was due to simple mechanical obstruction of the bowel (155).

Chickweed (Stellaria media) has been found to cause digestive disorder in lambs and sheep when eaten in large quantities (48), and has caused the death of many a lamb. It would appear to be due entirely to the formation of large lumps of the weed in the stomach, and subsequent fermentation (Farmer and Stockbreeder, Mar. 16, 1908).

According to Cornevin, Black Bindweed (P. Convolvulus L.) may prove injurious, owing to the occurrence of the hard, trigonous, and pointed “seeds” in cereal grains. Galtier published facts which show that oats which contain too many of the “seeds” may, by prolonged use, occasion a more or less serious enteritis, which is sometimes fatal, particularly when the grain is fed to greedy horses which scarcely grind their food (73). The fruits or “seeds” of Knot-weed (Polygonum Aviculare L.) may similarly prove injurious, and probably the seeds of other plants.

CHAPTER IX
CLASSIFICATION OF POISONS.

The classification of poisonous plants according to their effects is a somewhat difficult process, since more than one prominent symptom may be produced by the same plant. Two classifications, however, may be given as examples, the first that of Blyth, and the second that of A. B. Smith. These must be regarded as essentially applicable to human beings, though serving more or less as a guide in case of poisoning of farm live-stock.