The larkspurs are sometimes referred to in literature as knight's spurs, lark's-heel, lark's-claw and stavesacre. In France the common names are pieds d'alouette, herbe Sainte-Athalie, fleur d'amour.
Photo - F. Fyles - Larkspur.
They fall naturally into two groups, the tall and the low or dwarf species. The tall larkspurs, of which there are several species in Western Canada, grow from three to six feet high. The general outline of the leaves is round but they are deeply palmately cut into three to seven lobes like the leaves of the buttercup, the sections being very narrow or broadly wedge-shaped according to their number. The flowers are arranged in a narrow, sparingly-branched panicle or simple loose raceme from four to ten inches in length. Each flower is about an inch or an inch and a half broad, with a spur projecting at the back. The colour varies from a bright blue to a dull purplish blue, or in some species very pale violet and yellow. The seed vessels are about half an inch long, erect, dry, ending in a short beak. The seeds are numerous, small, with a loose coat. The plants are in bloom during June and July, sometimes earlier or later according to season and locality. The low larkspurs are similar in general appearance but are only six inches to three feet in height.
Practically all of the species of larkspur growing wild in Canada are native. They are common in Alberta and British Columbia.
The toxic nature of the. larkspurs has been recognized since early classic days, but it is only in comparatively recent literature that reference is made to them as some of the most important of the stock-poisoning plants. The greatest losses occur in North America. Chesnut says, "They have proved nearly as fatal to stock as the water hemlocks, and probably kill a larger number than any other class of plants."
As far as can be determined, the poisonous principles of only a few of the Canadian species have been studied. In 1913, Loy, Heyl, and Hepner isolated an alkaloid in an impure form from two species in Wyoming which also grow in Canada, D. nelsonii and D. glaucum. In 1910, Marsh and Clawson carried on feeding experiments with several species - including D. menziesii and D. bicolor, two low larkspurs of the West - which proved them to be highly poisonous to cattle. Two European species, D. Con-solida and D. Staphisagria contain the four alkaloids, delphinine which is very poisonous and bitter, delphisine which is extremely poisonous, delphinoidine also poisonous, and staphisagrine. No doubt the closely related Canadian species are of a similar nature. Marsh and Clawson, who have carried on extensive work with several species in the Western States, came to the conclusion that other species had the same properties as those experimented with, and that there was no marked difference in toxicity between the different species of larkspur.
The low larkspurs are poisonous during the whole season of their growth, but as they dry up and disappear in the early summer, poisoning usually occurs in the early spring.
The tall species live throughout the summer, but their toxicity diminishes after they flower, and they become coarse and less tempting. Therefore, although the seeds are very toxic, cases of poisoning occur chiefly in the spring when the green parts of the plant are most poisonous and afford an abundance of fresh green. In regard to the seeds, H. C. Long says they "are the most dangerous part of the larkspur, and should never be ground up with wheat should the two plants grow together." The loss of three head of cattle was reported to us (1918) from Barrhead, Alta., from eating the seed vessels of larkspur containing seeds. These had been cut and dried with the hay.
In the feeding experiments mentioned above, it was shown that the larkspurs were poisonous to cattle and horses but not to sheep. Horses, under ordinary conditions, do not eat sufficient quantity to do harm, so that losses from larkspur poisoning are chiefly confined to cattle. Pott states that D. Consolida is an acute narcotic poison to horses and cattle. .
The general symptoms of poisoning both from the tall and the low larkspurs are as follows: salivation, nausea, vomiting, weakness, colic, twitching of the muscles of the sides and legs, convulsions, and general paralysis. If the animal does not recover, death usually occurs in a few minutes or a few hours.
Remedy and Means of Control: Marsh and Clawson found in their experiments with antidotes that beneficial results were obtained by using "hypodermically, injections of physostigmin salicylate, pilocarpin hydro-chlorid, and strychnin sulphate, followed by hypodermic injections of whisky when needed."
They also pointed-out that "if in the beginning of the poisoning some remedy could be used which would quickly stimulate the intestinal excretion, it might serve to save the lives of animals."
As regards the eradication of larkspur, choice of methods must depend entirely upon conditions and circumstances. It may be pointed out that the loss of a single steer will cover a large amount of the cost of grubbing out this weed. The yearly loss of several head of cattle on a single farm and the cost of destroying the weed is best calculated by the owner. Where entire extermination is impossible, the first year or two, the number of the plants may be so reduced as to avoid actual loss by poisoning. In most cases the surest means of killing the plant is to cut off the roots from six to eight inches below the surface of the soil. The work should be done thoroughly to prevent the growth of new shoots. All tops cut off should be destroyed at once.