Botanical Name: Asclepias perennis
Common Name: White Swamp Milkweed, Aquatic Milkweed
Description: All of the milkweed species I sell are Florida ecotype plants that my suppliers grow in the North Central region of Florida. I use no pesticides on my milkweeds, neither do my suppliers.
White swamp milkweed is an erect, herbaceous perennial wildflower native to Florida that occurs naturally in floodplain swamps, marshes and wet ditches, and along riverbanks. Like most members of the Asclepias genus, it is a larval host plant for Monarch, Queen, and Soldier butterflies. The plant contains a milky latex that is toxic to most animals, but Monarch, Queen, and Soldier caterpillars are adapted to feed on them despite the chemical defense. The flowers are an important nectar source for native bees, honey bees, bumble bees, wasps, and butterflies. It is an important part of Integrated Pest Management because it attracts predatory or parasitoid insects that prey on pest insects.
Flowers are white to pale pink and born in flat terminal or axillary umbels. Individual flowers have five reflexed corollas and an upright corona. The unopened buds have pink apices. One inflorescence can produce up to 25 flowers. It typically blooms in late spring through early fall. Leaves are dark green, elliptic to lanceolate, and glabrous. They are relatively long, 3 – 5″, with short petioles and entire margins. Leaf arrangement is opposite. Can be semi-evergreen to evergreen in mild winters. The fruits are erect follicles that split along a single suture to release the seeds. The seeds of this species are unique compared to most other milkweeds, which occur in open landscapes and have fluffy seeds that are dispersed by the wind. Instead, this plant, being a resident of swampy habitats, has winged seeds that are designed to float on the surface of the water and are dispersed with flood events.
White swamp milkweed works well in mixed butterfly and wildflower gardens planted along pond edges, bog gardens, and rain gardens. It grows 1-3′ tall. Likes to grow in sun, part sun, or part shade areas of your garden. It does well in a container with only a few drainage holes. It can tolerate short periods of drought once established, but looks much better if soil is kept moist. It does adapt to regular gardening environments as long as it is not an extremely dry area. It might go dormant in the summer if it doesn’t get enough water. White swamp milkweed is easy to propagate from seed. Seedlings may flower as early as three to four months. Is deer and rabbit resistant because of its toxic milky sap.
Not salt tolerant of inundation by salty or brackish water. Low/no tolerance of salty wind or direct salt spray.
This plant in 1-gallon containers is 8-15″ tall.
Plant Lore: The genus Asclepias is named for Asclepius, the Greek god of healing, because some Asclepias species, such as A. tuberosa, are known to have medicinal properties even though the plants have a toxic sap. The species epithet perennis is Latin for “perennial.”
Florida Hardiness Zones 8 – 10