Common Milkweed

Asclepias syriaca

Alice B. Russell

Common Milkweed is an important plant because so many species of insects depend on it. Monarch Butterflies, Milkwee Bugs, and Milkweed Leaf Beetles only eat milkweed, and could not survive without it. Many other species of insects use milkweed as their primary food source, or as a major food source.

Common Milkweed grows up to six feet tall. It has large, broad leaves, usually four to ten inches long. They sometimes have red veins.

This plant is found in fields, gardens, and along roads.

Common Milkweed flowers are pinkish-purple clusters which often droop.

Fruits are green pods which turn brown before bursting open to let out fluffy seeds.

Mark Moran

Alice B. Russell

Milkweed seeds are spread by the wind, which catches the fluffy part and carries the seed for long distances.

Milkweed can spread quickly underground as well, by rhizomes. Rhizomes are roots that produce new roots. These new roots sprout new plants.

Through rhizome spreading, Common Milkweed forms a colony that quickly crowds out other plants.

Common Milkweed, when broken, lets out a milky sap. This sap has poisons in it, called Cardiac Glycosides. Some animals can eat the glycosides and not be harmed. When the Monarch butterfly's caterpillar munches the leaves of milkweed, the glycosides go into its body, making the caterpillar poisonous to predators. Even after the caterpillar has changed into an adult butterfly, it keeps the glycosides in its body.

Milkweed flowers bloom from June to August, and are visited by many species of moths, butterflies, bees, and other insects. The flower nectar and pollen does not have glycosides in it, so these animals do not become poisonous.

Milkweed is a shelter and hiding place for other species as well. Yellow Jackets eat bees and flies which get trapped in the flowers, and crab spiders ambush visiting insects.

Relationships in Nature:

Animals Using as Food Source

Animals Using as Shelter

Associations With Other Plants



Goldenrod Spider

Silver Maple

Eastern Yellow Jacket Po

Milkweed Bug

American Dog Tick


Chinese Mantid FP

Green Lacewing

Chinese Mantid

Smooth Crabgrass

American Dog Tick FP

Eastern Tiger Swallowtail

American Goldfinch

Queen Anne's Lace

Ruby-throated Hummingbird Po

Painted Lady

Black and Yellow Argiope

Smooth Sumac

Eastern Tiger Swallowtail Po

Mourning Cloak

Carolina Chickadee

Red Clover

Clouded Sulphur Po

Great Spangled Fritillary

Eastern Mole

Devil's Beggar-tick

Honey Bee Po


White-footed Mouse

Lamb's Quarters

Mourning Cloak Po

Eastern Black Swallowtail

Green Lacewing

Common Ragweed

Painted Lady Po

Pipevine Swallowtail


Golden Northern Bumble Bee Po

Pearl Crescent

Black-eyed Susan

Green Lacewing FP

Honey Bee

Bushy Aster

Pipevine Swallowtail Po

Golden Northern Bumble Bee

Kentucky Bluegrass

Monarch Pa

Black Carpenter Ant

Common Mullein

Organ-pipe Mud Dauber Po

Ruby-throated Hummingbird

Cicada Killer

Eastern Yellow Jacket

Fungus Gnat

Clouded Sulphur

Bald-faced Hornet

Relationship to Humans:

Common Milkweed is considered by many to be a pesky garden weed. Others, however, value it as a great attractor of wildlife, especially butterflies. It is poisonous to humans, so do not eat it. The fluffy seeds of milkweed are sometimes used as insulation or stuffing for life jackets.


Asclepias syriaca


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