This delicate milkweed with narrow leaves and stems may blend into the background when not in bloom, but its wildlife value still packs a punch. As one of the last milkweeds to flower, it’s an important late-season host plant for monarch larvae. It’s also one of the most widely distributed of all milkweeds in America, though it tends to be only lightly scattered across Ohio. It prefers full sun and open spaces and tops out at 2 feet, which makes it a good companion for shorter native prairie plants. It grows in a wide range of soils and is tolerant to drought and poor soils.
Whorled milkweed has unusually narrow leaves--almost like blades of grass—that are arranged densely in whorls (verticillate means “whorled”) of 3-6 along the stem. The longer lower leaves may droop, while the upper leaves are perkier. The ethereal clusters of 10-20 tiny, cream-colored flowers grow in umbels on the upper part of the plant and stem tips from July to September. The fruits, or pods, are also on the slender side, stuffing as many seeds as possible into their green casings. When the pod splits, the flat, brown seeds have tails of silky white fluff to carry them away in the wind.
Native habitats include thin, barren outcroppings; dry fields and prairies; sandy open woods; and roadsides. This is a good plant for naturalized areas, meadows, slopes or banks, and pollinator gardens.
Grows 2’ tall.
Prefers full sun but tolerates some shade.
Grows in average, dry-to-moist, well-drained soils, including clay, loam, and sand.
Greenish-white flowers appear in umbels 1-3” across from July to September. Green pods are very narrow, smooth, and 3-4” long. They split open to release numerous seeds with comas for wind dispersal September-October.
Leaves are thin and linear, about 3” long, with pointed tips and bases. The stem is green, slender, and sturdy. Milky sap irritant leaks from broken stems and leaves.
Host plant to 12 species of Lepidoptera larvae, including Isabella tiger moth, cecropia silkmoth, and unexpected cycnia. The nectar of the flowers attracts many kinds of insects, including honey bees and native long- and short-tongued bees, wasps, flies, butterflies, skippers, and beetles.
Medicinal, Edible, and Other Uses:
This plant contains cardiac glycosides and resinoids, which are toxic.
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