Weeds Profile - Milkweed
Table of Contents
English - common milkweed, (also green, swamp,
and whorled milkweed species)
French - asclépiade commune (asclépiade
a fleurs vertes, asclépiade incarnate and asclépiade
Latin - Asclepias syriaca L., Asclepias
viridiflora Raf. Asclepias incarnata L., Asclepias verticillata
- Other provinces - noxious in Quebec (common), Manitoba (common
- Canadian Federal Seeds Act - no
- U.S. Federal Noxious Weed - no
- U.S. Noxious State Reg - 1 state (Minnesota (common)
- Pub 505 - Milkweed species are generally thought to be poisonous
to livestock. Pub 505 suggests that there is some evidence to
suggest that common milkweed is toxic, and that other species
are highly toxic.
- NE Weeds - not mentioned
- Canadian Poison Plant - Canadian Poison Plant - This plant has
poisoned sheep in the eastern United States. The plant contains
cardiac glycosides, which are toxic to animals (Reynard and Norton,
Joubert 1989). (A dozen sheep died after ingesting large amounts
of common milkweed in Maryland. The plants, which were almost
the only vegetation available during a drought, are normally distasteful
to livestock (Reynard and Norton 1942). )
- Cornell Poison Plant - not listed
- Indiana Toxic Plants:
- Toxicity Rating: Low to moderate. Milkweeds are unpalatable,
and have variable toxicities. Death is not likely unless large
quantities are consumed.
- Animals Affected: All animals may be affected. Sheep are
most at risk, but cattle, goats, horses, poultry, and pets
are also at risk.
- Dangerous Parts of Plant: Stems, leaves, roots.
- Class of Signs: Gastrointestinal irritation (primarily vomiting
and diarrhea), incoordination, tremors, heart problems, respiratory
- Common milkweed occurs throughout Ontario in pastures, waste
areas, roadsides, and cultivated fields. Grows best in open areas.
Swamp milkweed occurs mostly in wet habitats of swamps and ditches.
Green milkweed is native to coarse soils. Whorled milkweed occurs
in dry open areas. Swamp and whorled milkweed relatively rare
compared to other milkweed species.
Method of Propagation
- Seeds, Wind blown, Roots/rhizome
- Glyphosate at medium to high rates (Roundup Ready crops) at
bud to early bloom stage, tolerant to 2,4-D, intermediate to dicamba.
Listed on Roundup label but not on 2,4-D or Banvel labels. Apply
herbicide at early bud (flowers mid summer) or in early fall.
Repeated mowing at 21 day intervals can be an effective control.
A single cutting will stimulate the sprouting of underground root
buds. Repeated cutting prior to fruit (pod) formation will reduce
- Host and food source for Monarch butterfly.
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