Pictured above: Whorled milkweed (Asclepias verticillata) by Eleanor Dietrich. Click on terms for botanical definitions. View post as a PDF.
Whorled milkweed (Asclepias verticillata) is one of the smaller, more delicate native milkweeds. It is found in pinelands throughout much of Florida. When not in bloom, it is easily overlooked. Its narrow leaves blend in with the grasses among which the plant typically grows. Like all milkweeds, Whorled milkweed is a larval host plant for the Monarch butterfly. It flowers late spring through late summer/early fall, attracting a variety of pollinators. It does not rely on pollinators to reproduce, however, as it spreads vegetatively.
Flowers are born in pedicellate umbels in groups of 15–20. The corolla is reflexed and white to greenish-white with tips that may be tinged in reddish-purple. Pedicels are purplish. Leaves are long, linear and sessile. Margins may be entire or revolute. Leaves are arranged in whorls around the stem (hence the common name). Stems are thin and glabrous. Seeds are ovately flat with many fine, silky hairs (pappus) attached to their apices that aid in dispersal. They are born in smooth narrow follicles that split open as the fruit matures.
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. The species epithet verticillata refers to the verticillate (i.e. whorled) arrangement of the leaves.
Family: Apocynaceae (Dogbane family)
Native range: Nearly throughout
To see where natural populations of Whorled milkweed have been vouchered, visit www.florida.plantatlas.usf.edu/Plant.aspx?id=3470.
Hardiness: Zones 8A–10B
Soil: Moderately moist to moderately dry, sandy to calcareous soils
Exposure: Full sun to minimal shade
Growth habit: 1–3’ tall
Garden tips: Whorled milkweed may be used in a moist wildflower garden. It may need to be reseeded periodically to maintain a population.
Caution: Whorled milkweed is considered the most toxic of all milkweeds, specifically to livestock, and as such should not be planted where cattle are known to forage.
Whorled milkweed is occasionally available from nurseries that specialize in Florida native plants. Growers may post availability on www.PlantRealFlorida.org.
For more information on other Asclepias species, see these resources:
- Milkweed (from 20 Easy-to-Grow Wildflowers)
- Carolina milkweed (Asclepias cinerea)
- Largeflower milkweed (Asclepias connivens)
- Pinewoods milkweed (Asclepias humistrata)
- Swamp milkweed (Asclepias incarnata)
- Fewflower milkweed (Asclepias lanceolata)
- Longleaf milkweed (Asclepias longifolia)
- Savannah milkweed (Asclepias pedicellata)
- Butterly milkweed (Asclepias tuberosa)
- Green antelopehorn (Asclepias viridis)