Vascular Plants of North Carolina
Account for Whorled Milkweed - Asclepias verticillata   L.
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Section 6 » Order Gentianales » Family Apocynaceae
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AuthorL.
DistributionThroughout the Piedmont (though of spotty occurrence in the foothills); nearly throughout the mountains; found only at a few places in the Coastal Plain, mainly in the Sandhills (and disjunctly in Jones County).

This is very widespread species across the Eastern and Central parts of the continent. Ranges northeast to New England, northwest to MT, and south to the Gulf Coast. It is scarce on the South Atlantic Coast Plain, however.
AbundanceFairly common in the Piedmont, except rare to uncommon in the foothills; infrequent in the mountains, mainly in the central and southern counties. Infrequent in the Sandhills region of the Coastal Plain, but essentially absent elsewhere.
HabitatThis is a milkweed of full sun to only partial shade. It grows in thin, rocky, or otherwise dry (clay) soil, but in many habitats. It occurs in glades and barrens over circumneutral soil, in powerline clearings, near margins of flatrocks, dry woodland borders, and in better (more loamy) soils in pine/scrub oak sandhills. It does show some affinity for high pH soils, and is certainly more numerous in such sites than in strongly acidic dry/sandy places.
See also Habitat Account for General Dry-Xeric Glades and Barrens
PhenologyBlooms from June to September, and fruits from September to October. It has a longer blooming period than most other milkweeds, often flowering into very late summer.
IdentificationThis is a quite slender milkweed, growing only to about 1.5' tall; there may be a few small branches in the upper nodes. It has numerous very slender, linear leaves, not paired as in other milkweeds but in whorls of 3-6 leaves at a single node. Each leaf is 1-2" long and needle-like; thus, the vegetative plant has very little leaf surface and can be almost invisible amid grasses and other herbaceous plants unless in bloom. The flowers occur in several dense ball-like clusters from upper axils, each about 1.5" across. The flowers are pale greenish-white, leaning to off-white, and not at all striking at much distance. Nonetheless, this is a milkweed worth knowing for its unusual whorls of several needle-like leaves, rather than for its flowers or overall stature. It can grow in small colonies, but even so such colonies are not large and do not attract attention from much distance. Fortunately, it is widespread in the western 2/3rds of the state and should be a fairly familiar species to biologists.
Taxonomic CommentsNone

Other Common Name(s)Horsetail Milkweed
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