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Veterinary Medicine Library |
Dwarf Larkspur and Other Larkspurs (Delphinium tricorne Michx. and other species)
| Description | Distribution | Conditions of poisoning | Control | Toxic principle | Clinical signs | References
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Dwarf larkspur is an erect, little-branched herb 1 to 3 feet tall. Its leaves, alternately placed and slender-stalked, are deeply divided into 5 to 7 nearly separate lobes, each lobe itself again rather deeply lobed or toothed. Its stout stem ends in a flower-bearing part that carries several blue or white, spurred blossoms 1 to 1 1/2 inches long. Three short-pointed rather fragile, widely spreading pods about 1/2 inch long develop from each blossom. These pods contain numerous small, dark seeds.
The rocket larkspur (Delphinium ajacis L.), which is cultivated and sometimes escapes, may be recognized from the above general description. It is supposed, in common with all other larkspurs, to be poisonous.
The dwarf larkspur occurs principally in the southern third of Illinois, where it is most often found in ravines and along streams in wooded sections. Northward it becomes less frequent and probably does not grow in the northernmost two or three tiers of counties.
The rocket larkspur, also, is most abundant in southern counties, where it is most often found in open woods and fallow fields.
Larkspurs are among the early spring plants, blossoming in late April and May. Animals turned out to graze in woods in the spring may eat the plant, especially if other herbage is scant. Cattle are the animals most often poisoned. Horses are susceptible to the poisoning but generally avoid larkspurs. Sheep, although seemingly resistant, can be poisoned by large amounts. Fatal poisoning of an animal may result from a single day's consumption of 1 percent or less of the animal's body weight of larkspur plants.
Animals, especially cattle, should not be grazed in woodland pastures infested with larkspurs until there is an abundance of other herbage for them to browse. Heavily infested pastures probably should not be used until the larkspurs have been destroyed. In woods, where it is hard to use chemical weed-killers, the only way to eliminate the plant is to dig it out by the roots.
Although larkspurs contain several other alkaloids, the main poison is the glucoside delphinin.
Symptoms of larkspur poisoning vary according to the amount eaten and the animal's tolerance of the poison. Small amounts may cause loss of appetite, excitability, staggering, or muscular incoordination, and constipation. Severe symptoms include slobbering, nausea, vomiting, colic, bloating, and convulsive movements. Fatal poisoning brings convulsions and paralysis of the respiratory system. Autopsies reveal inflammation, or at least congestion of the windpipe, stomach and small intestine, congestion of the superficial blood vessels, and dark, extremely congested kidneys.
Delphinium entry in Wikipedia
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