SafePlants

Asclepias incarnata: Swamp Milkweed

Asclepias incarnata, commonly known as swamp milkweed, is a captivating herbaceous perennial celebrated for its vibrant blooms and vital role in supporting monarch butterflies. Other common names include rose milkweed, rose milkflower, swamp silkweed, white Indian hemp, red milkweed, and marsh milkweed.

Considerations for Pets and Children

• The plant produces a juice that, while described as "less milky" than other species, might still be a consideration.
• Following flowering, seed pods develop and rupture, releasing seeds with long, silvery-white hairs. These small parts could be a potential hazard.

Taxonomy and Nomenclature

• Scientific Name: Asclepias incarnata L.
• Family: Asclepiadaceae (Milkweed Family)
• The genus name Asclepias is derived from the name of the Greek god of medicine.
• Plant Symbol: ASIN

Distribution and Habitat

• Native to North America.
• Commonly found in swamps, river bottomlands, marshes, meadows, fields, shores of rivers or lakes, and other wetland environments.
• Specifically noted as native to southern Ontario and a Missouri native plant.

Morphology and Growth Habits

• A perennial wildflower that can grow to be 2-6 feet tall, depending on conditions. Some sources mention heights of 1-2 feet or 4-5 feet.
• Characterized by ascending to erect, unbranched flowering stems.
• Leaves are opposite, narrow, and can reach up to 6 inches in length.
• Flowers are arranged in 2 to 3-inch flat clusters, typically pink to rosy red. Some cultivars, like 'Cinderella', exhibit red to pink coloration.
• Spreads via underground stems called rhizomes. Some sources claim it does not spread aggressively by rhizomes, making it a good choice for home gardens.
• Following flowering, typical milkweed seed pods develop, which rupture to reveal seeds with long, silvery-white hairs.

Ecological Role

• A major host plant for monarch butterfly larvae. Monarchs obtain poisonous chemicals from milkweed plants during their larval stage.
• A great nectar plant, attracting butterflies. The flowers have a faint vanilla fragrance that is attractive to butterflies.
• Important pollinator plant.

Interactions with Other Organisms

• Monarch butterflies lay their eggs on swamp milkweed.
• Adult butterflies mate on or around milkweed.

Further Information

• USDA NRCS, Norman A. Berg National Plant Materials Center
• Dave's Garden (for gardening tips and ideas)
• Ontario Wildflowers (photos and information)