This section is from the book "A Guide To The Poisonous Plants And Weed Seeds Of Canada And The Northern United States", by Robert Boyd Thomson, H. B. Sifton. Also available from Amazon: A guide to the poisonous plants and weed seeds of Canada and the northern United States.
Other Common Names: Wild Parsnip, Spotted Hemlock, Beaver Poison, Musquash Root, Cowbane, Spotted Cowbane.
Several species of the Water Hemlock grow commonly in Canada. Parts of these are deadly in their effects. This fact was well known to the Indian by whom the loot, the most poisonous part, was sometimes used for self destruction, being very rapid in its action. Cases of accidental human poisoning also occur. The roots have a sweetish and not unpleasant taste, and a rather parsnip-like odour. They are occasionally eaten by children and even by adults, who mistake them for the aromatic roots of harmless plants.
Fig. 15. - Water Hemlock - Cicuta maculata. a Upper leaves and flower-clusters; b Thickened rootstock with cross-partitions, and fleshy roots about one-third natural size.
During May and June, 1900, Chesnut and Wilcox noted in Montana thirty-six cases of Water Hemlock poisoning among cattle, and one hundred and five among sheep. Thirty of the cattle and fifty of the sheep died. The poisoning occurs under various circumstances. Chesnut states that the seeds are sufficiently poisonous to cause loss when the mature plant is cut and fed with hay, but Marsh believes that this is a mistake. However this may be, there is no doubt of the poisonous character of the root and young shoot. Cases have been reported of horses killed by eating the roots upturned by the plow. Animals have also been reported to have been poisoned, especially in the spring, by drinking water from wet places where the Water Hemlock grew. The poison was considered to have got into the water from the juices of the roots crushed by the trampling of the animals themselves. Cases of poisoning by the young shoots are also on record. Although the stem and leaves of the mature plant contain little poison, it has been repeatedly proved that the young plant, six inches or so in height, contains it in sufficient quantity to be a source of much danger. This early spring stage is especially attractive when other green stuff is scarce, and the ground being wet at this season of the year the roots are readily pulled up by the grazing animal, and form an added menace. We are indebted to Dr. C. D. McGilvray, now Principal of the Ontario Veterinary College, for the details of an interesting case of stock poisoning by this spring growth of the Water Hemlock. It came under his observation when he was stationed at Winnipeg. Twenty-one head of cattle were turned out to pasture between 9 and 10 a.m. and at
3 p.m. nine were found dead and several sick, one of the latter dying while the herd was being removed. On examination of the place where the dead animals were found, a piece of marshy land near the shore of Lake Winnipeg, it was discovered that the whole area was overgrown by the young shoots of the Water Hemlock. The stomach contents of the dead animals proved to be composed chiefly of this young growth with a few roots.
In this particular area cattle had pastured in former years with impunity, the young Water Hemlock having been concealed by the previous year's growth of marsh grass, but this season the grass cover had been burned off. Another peculiar feature of the case was that the younger members of the herd were not affected. This apparent immunity was found to be due to their having been driven away from the tempting shoots by the older animals.
Some writers state that the plant is most poisonous in winter and spring. Others believe that the effects in autumn are just as deadly. All agree, however, that during the hot summer season a larger quantity may be eaten without harmful results. Jacobson has discovered the reason for this. In his investigations of the properties of cicutoxin, the poisonous constituent, he found that it is very sensitive to rises in temperature, becoming polymerized by heat.
The poison is very rapid in its action, and a very small quantity will produce death. Soon after eating severe abdominal pain manifests itself. Great mental excitement develops into a frenzy. There is often frothing at the mouth. Respiration is laboured and often irregular. The pulse is intermittent. Convulsions follow and death ensues, sometimes within fifteen minutes of the time when the poison was eaten, but more often in two or three hours.
Treatment is generally very difficult, owing to the rapidity and violence of the attack. In one case a cow was treated by opening the stomach as soon as symptoms were noticed, and removing the contents. This, together with a large enema of warm water and a drench of melted lard, produced a cure. Potassium permanganate solution is recommended as a chemical antidote, as is also tannin, but their effectiveness is in dispute. Chloral hydrate and morphin injections are useful for reducing the nervous symptoms and frenzy, the latter being preferable, perhaps, owing to its more rapid action.
Cicuta maculata L. is the most widely distributed Water Hemlock in Canada, growing in moist locations probably across the continent. It is from two to six feet tall and crowned with large compound umbels of white flowers, which are later replaced by ellipsoid fruits with large oil tubes. The lower leaves are large, and two or three times pinnate. The upper are smaller. All have long petioles, sheathing the stem completely at their insertion. The leaflets are lanceolate or oblong lanceolate and coarsely serrate. The stems are hollow, with solid partitions at the leaf nodes. The short, bulbous rootstock has many cross-partitions closely approximated, as may be seen by slicing it lengthwise through the centre. Around its base are smaller root-not unlike very small sweet potatoes in appearance.
The Oregon Water Hemlock, Cicuta vagans G., is found in British Columbia, and the States to the south.
It is of this species that Hedrick makes the statement that a piece of root the size of a walnut will kill a cow.
It is a somewhat smaller plant than the preceding and is distinguished from it by its orbicular fruits with small oil-ducts. The leaflets also are less sharply serrate.
The Bulbous Water Hemlock, Cicuta, bulbifera L., is found in the eastern provinces, Ontario, Manitoba, British Columbia, and the adjacent states to the south. Like the other species it is very poisonous. It is a slender plant, one to three and one-half feet high. Its leaflets are linear and sparingly toothed. The upper leaves have clusters of bulblets in their axils.