common milkweed

Asclepias syriaca


Well known a half century ago as an abundant roadside weed, common milkweed was extensively controlled by farmers and road crews across Wisconsin. The success of the weed management efforts caused a dramatic decline in the number of monarch butterflies that require milkweed plants milkweed plants as a place to lay their eggs and to nourish monarch caterpillars as they develop.

A recent scientific review recommended that the monarch butterfly be added to the federal Endangered Species list. That recommendation was rejected because there were not sufficient resources to enforce its protection under the law. Voluntary efforts are underway to increase milkweed numbers to protect and restore monarch butterfly populations.

Common milkweed is the largest and most abundant species of milkweed in Wisconsin. Other species include: butterfly milkweed, clasping milkweed, green-flowered milkweed, marsh (swamp) milkweed, poke milkweed, prairie milkweed, purple milkweed, wooly milkweed, and whorled milkweed. 


common milkweed

USDA Symbol: Common Name: Scientific Name:
ASSY common milkweed Asclepias syriaca

ITIS TSN: 30310

Category: Dicot


Kingdom: Plantae


Super Division: Spermatophyta

Division: Magnoliophyta


Class: Magnoliopsida

SubClass: Asteridae

Order: Gentianales

Family: Asclepiadaceae

Counties: Adams, Ashland, Barron, Bayfield, Brown, Buffalo, Burnett, Calumet, Chippewa, Clark, Columbia, Crawford, Dane, Dodge, Door, Douglas, Dunn, Eau Claire, Florence, Fond du Lac, Forest, Grant, Green, Green Lake, Iowa, Iron, Jackson, Jefferson, Juneau, Kenosha, Kewaunee, La Crosse, Lafayette, Langlade, Lincoln, Manitowoc, Marathon, Marinette, Marquette, Milwaukee, Monroe, Oconto, Oneida, Outagamie, Ozaukee, Pepin, Pierce, Polk, Portage, Price, Racine, Richland, Rock, Rusk, Sauk, Sawyer, Shawano, Sheboygan, St. Croix, Taylor, Trempealeau, Vernon, Vilas, Walworth, Washburn, Washington, Waukesha, Waupaca, Waushara, Winnebago, Wood

Natural Community: Mesic Prairie, Lake Dunes

Curtis Community: Wet-mesic Prairie, Bracken-grassland

Coefficient of Conservation: 1

Duration: Growth Habit: Native Status:
Perennial Forb/herb L48(N)CAN(N)

Active Growth Period:

After Harvest Regrowth Rate:


Carbon to Nitrogen Ratio:

Coppice Potential:

Conspicuous Fall Color: No

Fire Resistant:

Flower Color: Purple, White, Pink

Conspicuous Flower: Yes

Foliage Color: Dark Green

Foliage Light Porosity Summer:

Foliage Porosity Winter:

Foliage Texture:

Fruit/Seed Color:

Fruit/Seed Conspicuous: Yes

Growth Form: Rhizomatous

Growth Rate:

Height at Base Age (Max):

Height at Maturity: 6

Known Alelopath: No

Leaf Retention: No


Low Growing Grass: No


Shape and Orientation: Erect

Toxicity: Moderate

Height (min): 36

Height (max): 72

Root Type: Rhizome

Leaf Type: simple

Leaf Arrangement: opposite

Leaf Shape: lanceolate, oblong, ovate, eliptic

Leaf Margin: entire

Vein Pattern:

Bloom Period: Commercial Availability: Fruit/Seed Abundance:
Late Spring, Early Summer Routinely Available Medium
Fruit/Seed Period Begin: Fruit/Seed Period End: Fruit/Seed Persistence:
Fall Fall No
Propogated by Bare Root: Propogated by Bulbs: Propogated by Container:
Yes No Yes
Propogated by Corms: Propogated by Cuttings: Propogated by Seed:
No Yes Yes
Propogated by Sod: Propogated by Sprigs: Propogated by Tubers:
No No No
Seeds per Pound: Seed Spread Rate: Seedling Vigor:
64000 Moderate High
Small Grain: Vegetative Spread Rate: Propagation Treatment:
No Moderate
Days to Stratify: Direct Sowing Time:
10 Spring, Early Summer, Fall

Benefits: Butterflies, Host Plant, Pollinators

Berry/Nut/Seed Product: Christmas Tree Product: Fodder Product:
No No No
Fuelwood Product: Lumber Product: Naval Store Product:
No No No
Nursery Stock Product: Palatable Browse Animal: Palatable Graze Animal:
Yes -- Low
Palatable Human: Post Product: Protein Potential:
No -- --
Pulpwood Product: Veneer Product:
No No
Benefits: Wildlife Food Value: Wildlife Cover Value:
Butterflies, Host Plant, Pollinators Low Low


  1. Ladybird Johnson Wildflower Center – Asclepias syriaca
  2. Monarch Watch – Milkweed Propagation
  3. Spreading Milkweed, Not Myths
  4. USDA Plants Database – Asclepias syriaca
  5. Wisflora Database – Asclepias syriaca