Eastern whorled milkweed
General poisoning notes:
Eastern whorled milkweed (Asclepias verticillata) is a native plant found in fields in parts of southern Canada. It has caused poisoning in experimental feeding tests in sheep. Large quantities of fresh plant were administered with a balling gun at about 2.2% of body weight, causing symptoms of poisoning (Marsh and Clawson 1921). The early literature is rife with contradictions in determining the scientific names of various milkweeds. Asclepias verticillata was termed Asclepias verticillata var. geyeri in Marsh and Clawson (1921). For more information on Asclepias taxonomy see Woodson (1954).
Nomenclature:
Scientific Name: Asclepias verticillata L.
Vernacular name(s): eastern whorled milkweed
Scientific family name: Asclepiadaceae
Vernacular family name: milkweed
Asclepias verticillata L.
Geographic Information
Manitoba, Ontario, Saskatchewan.
Toxic parts:
Flower buds, leaves
Toxic plant chemicals:
Galitoxin
Animals/Human Poisoning:
Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.
Sheep
General symptoms of poisoning:
Agitation, bloat, breathing, labored, convulsions, death, depression, opisthotonos, pupil dilation, temperature, elevated, trembling, weakness, posterior.
Notes on poisoning:
Experimental feeding of fresh eastern whorled milkweed caused poisoning in sheep. The animals fell down and went through characteristic running movements. The head and jaws occasionally moved compulsively. The pulse was often weak. Ingesting 2.2% of body weight was necessary to produce serious poisoning in sheep. Animals do not normally eat these distasteful plants or other milkweeds (Marsh and Clawson 1921).
