Tall larkspur
General poisoning notes:
Tall larkspur (Delphinium glaucum) is a native herb found in central and western Canada. The plant is poisonous to cattle and can be poisonous to horses and sheep when ingested in higher amounts. In an experiment with Delphinium barbei (not found in Canada), six times as much plant material (per kilogram of body weight) was needed to poison sheep than to poison cattle. Why cattle are sensitive to larkspur poisoning is not understood. The alkaloid methyllycaconitine causes curare-like effects on the skeletal muscles and can cause motor paralysis, followed by death from asphyxiation (Nation et al. 1982, Cheeke and Schull 1985, Olsen and Manners 1989).
Description:
Stems (60-)100-200(-300) cm; base usually green, glabrous, glaucous. Leaves cauline, 15-20, absent from proximal 1/5 of stem at anthesis; petiole 1-14 cm. Leaf blade round to pentagonal, 2-11 × 3-18 cm, margins seldom laciniate, glabrous; ultimate lobes 5-9(-15), width 5-24(-35) mm, tips abruptly tapered to mucronate apex; midcauline leaf lobes more than 3 times longer than wide. Inflorescences (13-)40-90(-140)-flowered; pedicel 1-3(-5) cm, puberulent or glabrous; bracteoles 2-6(-10) mm from flowers, green to blue, linear, 2-7 mm, puberulent or glabrous. Flowers: sepals bluish purple to lavender, puberulent, lateral sepals forward pointing to spreading, 8-14(-21) × 3-6 mm, spurs straight, ascending to ca. 45° 10-15(-19) mm; lower petal blades ± covering stamens, 4-6 mm, clefts 1-3 mm; hairs centered, mostly near base of cleft, white. Fruits 9-20 mm, 3.5-4.5 times longer than wide, glabrous to puberulent. Seeds wing-margined; seed coat cells elongate but short, surfaces smooth or roughened. 2 n = 16.
Delphinium glaucum S. Wats.
Nomenclature:
Scientific Name: Delphinium glaucum S. Wats.
Synonyms: Delphinium glaucum S. Watson
Vernacular name(s): tall larkspur
Scientific family name: Ranunculaceae
Vernacular family name: crowfoot
Geographic Information
Alberta, British Columbia, Manitoba, Northwest Territories, Ontario, Quebec, Saskatchewan, Yukon Territory.
Notes on Poisonous plant parts:
All parts of larkspur plants contain alkaloids. Cattle have been poisoned after browsing on the aboveground plant material. Sheep and horses have been experimentally poisoned by various larkspur species, but they are much more tolerant of the toxic alkaloids (Olsen and Manners 1989).
Toxic parts:
All parts, leaves, seeds.
Notes on Toxic plant chemicals:
Methyllycaconitine, a diterpene alkaloid, is considered to be the most toxic of the alkaloids occurring in larkspurs that are likely to be grazed by cattle on rangelands. Many other alkaloids occur in larkspurs, but they are much less toxic than methyllycaconitine. The LD50 of this chemical on mice is 3.2 mg/kg administered intravenously. It has a pronounced curare-like effect on skeletal muscle (Olsen and Manners 1989).
Toxic plant chemicals:
Methyllycaconitine.
Methyllycaconitine
Chemical diagram(s) are courtesy of Ruth McDiarmid, Biochemistry Technician, Kamloops Range Station, Agriculture and Agri-Food Canada, Kamploops, British Columbia, Canada.
Animals/Human Poisoning:
Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.
