Whorled Milkweed

Ecology & Conservation

Proximity Score

2

Native Status

❌ Outaouais ❌ Ottawa ❌ QC ✅ ON

Closest Direction

SE

CEC Eco-Regions

8 – Eastern Temperate Forests, 8.1 – Mixed Wood Plains, 8.1.7 – Northeastern Coastal Zone

Rarity Notes

Ranked S4 (Apparently Secure) in Ontario and G5 globally. Not listed under SARA. In the Ottawa region, considered rare and possibly native only at a single site (Grainger Side Road) on thin soil over limestone bedrock, with native populations of Provincial Conservation Concern (S2) in Ontario per Brunton 2005. New England populations are quite rare and restricted to calcareous substrates.

S22 G5, S4-ON; S26 SARA not listed; S62 rare in Ottawa; S61 rare in New England

Rarity Ranks

QC SNA – Not Applicable, ON S4 – Apparently Secure

Migration

Stable

Ecological Context

A slender, rhizomatous prairie milkweed of dry, open habitats. Typical in sandy or gravelly prairies, oak savanna openings, limestone ledges, and roadsides on well-drained soils. In Michigan, characteristic of dry sunny roadsides and abandoned gravel pits, spreading rapidly along highway corridors via creeping rhizomes. At the northeastern limit of its range in New England, where it is restricted to calcareous cliffs and ledges.

S7 prairies, oak savanna, roadsides, gravelly; S61 cliffs, ledges, woodlands; S48 limestone bedrock habitat

Permaculture & Companion Planting

Roles

Fortress/Barrier, Insectary Plant, Pollinator Attractor

S73/S29/S72 Evidence: 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)]

Medicinal Properties

ℹ

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Category

Diaphoretic, Stimulant, Gynecological Aid, Snake Bite Remedy, Respiratory Aid

S28 Choctaw: sudorific (diaphoretic), stimulant, snake bite; Hopi: gynecological aid (milk flow); Navajo: nose and throat medicine

Notes

Multiple Indigenous nations used this species medicinally. Choctaw people used the root as a sudorific (diaphoretic) and stimulant, and chewed the root with saliva swallowed and a strong decoction taken for snakebite. Hopi people prepared an infusion of the entire plant for nursing mothers with scanty milk flow. Navajo people used the plant for nose and throat troubles. Seven distinct medicinal use records across four Indigenous nations.

S28 Choctaw Drug (3 uses), Hopi Drug (1 use), Lakota Drug (1 use), Navajo Drug (2 uses)

Edibility & Foraging

ℹ

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✅ Edible   

Foraging Notes

Hopi people boiled the leaves and young shoots with meat and ate them. As with other milkweeds, proper preparation is important due to the presence of cardiac glycosides. Only one ethnobotanical food record exists, indicating this was not a widely used food species.

S28 Hopi Food: leaves and young shoots boiled with meat; S4 cardiac glycosides present

Toxicity

⚠️ Moderate Toxicity

Despite a USDA/Cornell toxicity rating of None, this species contains cardiac glycosides and resinoids that are toxic to livestock, particularly cattle and sheep. Considered one of the more poisonous milkweeds to livestock in range areas. All parts are toxic if consumed in large quantities; symptoms include vomiting, stupor, weakness, and spasms. The OWSL notes it is toxic to mammals if ingested. The None rating likely reflects low risk to humans under normal contact conditions.

S4 POISONOUS PARTS: All parts, cardiac glycosides and resinoids; S3 toxic to mammals; S4 one of more poisonous milkweeds to livestock

Seed Source

• Localeaf
• NANPS
• NANPS