20. DWARF LARKSPUR, STAGGERWEED, POISON WEED

Delphinium tricorne

CULTIVATED LARKSPUR

Delphinium ajacis

(buttercup family)

TOXICITY RATING: Moderate for Indiana. These plants are a more serious threat in the western ranges.

ANIMALS AFFECTED: Cattle are the primary animals affected; toxin can also affect other ruminants as well as horses.

DANGEROUS PARTS OF PLANT: All parts, especially seeds and young leaves.

CLASS OF SIGNS: Nervousness, incoordination, staggering, salivating, bloating, abnormal heart beat, breathing difficulty, paralysis, convulsions, death.

PLANT DESCRIPTION: These short annual or perennial herbs (fig. 20), 1/2 to 4 feet high, bear alternate, deeply-lobed ("crowfoot") leaves and elongate clusters of spurred white, blue, or purple flowers in the spring. Roots grow in tuberous clusters. This weed commonly grows in rich open woods, along

streams, in old fields, along roadsides, and on sand hills. Wild larkspur is most common in the southern two-thirds of the state, but the equally poisonous cultivated larkspur may be found in gardens statewide.

SIGNS: Larkspur is primarily a problem in western ranges, especially with cattle. Apparently, the plant is palatable, which increases the risk of clinical toxicosis. The toxicity of larkspur varies, with the highest periods of toxicity occurring during early growth, and when the plant goes to seed. The toxin is a mixture of alkaloids, including ajacine and delphinine, and blocks communication between nerves and muscles (like curare). Signs appear within a few hours of ingestion. Approximately 1/4 pound of larkspur per 100 pounds body weight may be lethal for cattle. A higher dose is needed before sheep and horses show clinical signs.

FIRST AID: There is no antidote for larkspur poisoning, and treatment is supportive. A veterinarian needs to be called if the animals are bloated, or if consumption was very recent (the veterinarian may be able to empty the stomach or rumen). Affected animals should not be handled any more than necessary, since stress will worsen the signs.

SAFETY IN PREPARED FEEDS: Larkspur remains toxic when dry, therefore hay and other prepared feeds will be toxic.

PREVENTION: Do not let animals (especially cattle) graze larkspur, particularly during the early growth and seed stages. Keeping pastures mowed will greatly reduce the number of larkspur plants.