In Maryland, Whorled Milkweed is an uncommon plant that grows on the piedmont and Ridge and Valley. According to the MD Natural Heritage Program, Whorled Milkweed prefers, "a variety of dry, open-canopy barrens, thin-canopied woodlands and outcrops and over a variety of substrates ranging from acidic (dry sands) to mafic (limestone, shale) and ultramafic substrates (serpentine)." The MD Natural Heritage Program also states that the coastal plain populations of Whorled Milkweed probably relied on fire, and are now to be considered extirpated. Whorled Milkweed is tracked by the MD Natural Heritage Program, and is on the state watch list with a rank of S3.
Whorled Milkweed looks like no other Maryland milkweed species. The leaves are linear and arranged in whorls along the stem. The flowers are smaller than most other milkweed species. They are arranged in clusters, whitish when mature, with reflexed corolla petals that are often tinged with purple/pink. The Maryland Biodiversity Project has blooming dates between 7/1 and 8/31.
Monarch caterpillars are known to occasionally use Whorled Milkweed as a host plant.
There are 107 records in the project database.
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