Swamp Milkweed

Swamp Milkweed

Asclepias incarnata

Plant Type
Forb (Deciduous)
Landscape Layer
Herb
Sun
☀️ Full Sun, ⛅ Part Sun, ☁️ Shade
Moisture
💧 Regular, 💧💧 High, 💧💧💧 Wet
Soil
Clay, Loam, Silt, Organic / Peat, Calcareous
Bloom
September, October
Sociability
S2 – Small groups

Pollinator Value

🐛 Larval Host
Danaus plexippus, Pyrrharctia isabella, Hyalophora cecropia, Euchaetes egle, Cycnia tenera, Phragmatobia lineata, Trichordestra legitima, Spodoptera frugiperda, Melanchra adjuncta, Papaipema nebris

S13+S15 10 verified Eastern NA

❄️ Winter Food Source
Seed pods (follicles) persist into winter and split open to release wind-dispersed seeds with silky comas. The persistent pods and residual seeds provide minor foraging opportunities for overwintering birds. The Avian Diet Database records Asclepias in the diet of the Plain Chachalaca, though this species does not occur in ON/QC. Standing dead stems also provide overwintering habitat for native insects.

S57 Asclepias genus-level; S4 seed pods persist into winter; S10 seedpods split open in fall

Ecology & Conservation

Proximity Score
0
Native Status
❌ Outaouais ✅ Ottawa ✅ QC ✅ ON
Closest Direction
Local
CEC Eco-Regions
5 – Northern Forests, 5.2 – Mixed Wood Shield, 5.2.3 – Algonquin/Southern Laurentians
Rarity Notes
Globally secure (G5) with a national rank of N5 in both Canada and the United States. Secure (S5) in Ontario; not formally ranked (SNR) in Quebec. Not listed under SARA or COSEWIC. Common throughout its range in wet habitats across eastern North America.

S22 G5, N5, S5 ON, SNR QC; S26 not SARA listed

Rarity Ranks
QC SNR – Not Ranked, ON S5 – Secure
Migration
Stable
Ecological Context
Swamp milkweed occupies wet to moist open habitats including floodplain margins, swamp edges, wet meadows, fens, marshes, and drainage ditches. In the Ottawa Valley it is common along rivers and lake shores in mucky clay or silty organic soils. It tolerates temporary flooding but not prolonged drought. The species is a key component of wetland pollinator habitat, producing abundant nectar that attracts a wide diversity of insects and hummingbirds.

S10 habitats; S7 wet ground habitats; S62 Common in Ottawa; S4 wetland habitats

Permaculture & Companion Planting

Roles
Fire Retardant, Fortress/Barrier, Insectary Plant, Pollinator Attractor

S73/S29/S72 Evidence: Fire Retardant: S73 [HIGH]: S11 Fire Resistant = Yes (definitional)] | Fortress/Barrier: S61 keyword match: thorns? (supporting signal only)] | Insectary Plant: S64 NPPBI 'beneficial insects' flag] | Pollinator Attractor: S73 [HIGH]: S64 Xerces listed (source-classified)]

Notes
Swamp milkweed functions as a powerful pollinator attractor and insectary plant in wetland guilds and rain garden designs. Its prolific nectar draws beneficial insects that provide biological pest control. Best sited in wet to moist zones alongside other wetland perennials. The rhizomatous root system helps stabilize wet soils. PFAF rates it for food forest and carbon farming applications.

S29 food forest, carbon farming, attracts wildlife; S64 insectary plant, pollinator attractor

Medicinal Properties

Always consult a qualified healthcare provider before using any plant for medicinal purposes. The information provided is compiled from secondary sources for educational purposes only.

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Category
Anthelmintic, Carminative, Diuretic, Emetic, Laxative, Stomachic, Dermatological Aid, Kidney Aid, Strengthener

S29 Anthelmintic, Carminative, Diuretic, Emetic, Laxative, Stomachic; S28 Dermatological Aid, Kidney Aid, Strengthener

Notes
Extensive Indigenous medicinal use documented. The Meskwaki used a root infusion to expel tapeworms within one hour and employed the root as a carminative, cathartic, diuretic, and emetic. The Iroquois used root decoctions for kidney ailments, lame backs, urinary disorders, and as a strengthening wash. The Chippewa bathed children and adults in root infusions as a strengthener. Roots have also been used to treat asthma, rheumatism, and syphilis, and as a heart tonic.

S28 21 Moerman uses across Chippewa, Iroquois, Meskwaki, Menominee; S29 traditional medicinal uses

Edibility & Foraging

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✅ Edible   

Foraging Notes
Young shoots are cooked as an asparagus substitute. Unopened flower buds are cooked and taste somewhat like peas. Young seed pods (3-4 cm) are cooked with a pea-like flavour. Flower clusters can be boiled into a sugary syrup. The Menominee added flower heads to cornmeal mush and dried them for winter use. All parts are toxic raw due to cardiac glycosides and must be thoroughly cooked before consumption.

S29 edible parts and preparation; S28 Menominee food uses; S4 edible cooked

Toxicity
⚠️ Moderate Toxicity

Contains cardiac glycosides and resinoids typical of the milkweed genus. All parts of the plant are toxic when consumed raw, causing vomiting, stupor, weakness, and spasms in large quantities. The milky latex sap is a skin irritant. Mammalian herbivores avoid the bitter, toxic foliage. While the plant has documented edible uses, all parts require thorough cooking to reduce toxicity. Moderate toxicity rating reflects the need for preparation before consumption.

S11 Toxicity=Moderate; S29 toxic resinoids, alkaloids, cardiac glycosides; S4 cardiac glycosides and resinoids; S10 foliage toxic with cardiac glycosides

Seed Source

  • Localeaf
Swamp Milkweed