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.
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.
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.
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