Asclepias purpurascens aka Purple Milkweed

Asclepias purpurascens, or purple milkweed, is a perennial wildflower. It belongs to the dogbane family, Apocynaceae. Its native range covers central and eastern North America. It grows in woods, thickets, glades, and open meadows. Other habitats include stream banks, wet meadows, and dry ridges. It is rare in North Carolina. There, it occurs in both damp sites and dry woods.

Garden plants reach 2–4 feet (0.61–1.22 metres) tall. They can spread to 3 feet (0.91 metres) wide. NC State gives a shorter height range of 2–3 feet (0.61–0.91 metres). Strong green stems stand upright and may bear fine hairs. Broken stems release a milky sap. Simple leaves grow in opposite pairs on short stalks. They have pointed tips and oval to lance-shaped blades. Leaves reach 0.67 feet (0.20 metres) long. Their upper sides are dark green, with fine hairs beneath. The edges may wave or curl upward.

Flowers open from May through July in rounded umbels. Their colour ranges from deep rose pink to purple. Each small flower has five petals. Bees and butterflies visit the blooms for nectar. Monarch caterpillars feed on the leaves. The plant also draws moths, hummingbirds, and other useful insects. Seed pods develop from July through October. These follicles reach 0.5 feet (0.15 metres) long. They split when ripe and release many seeds. White hair tufts help the wind carry each seed. The pods also have value in dried arrangements.

Grow purple milkweed in full sun and well-drained soil. It also accepts some shade. Sources describe suitable soils as dry through moist. It can grow in clay, loam, sand, and rocky ground. It tolerates drought, poor soil, and deer. Its USDA hardiness range is zones 3–8. Seeds offer a way to raise new plants. Its spreading roots are best left undisturbed. Meadows, native plantings, and butterfly gardens suit its form. Sources disagree about how strongly it spreads. Missouri Botanical Garden describes restrained spread; NC State warns of aggressive growth.

Neither source reports major disease trouble. Aphids can cause problems, though many milkweed insects cause little harm. Milkweed bugs can damage the seed pods. Aphid control may also harm monarch larvae and useful insects. The plant poses risks to people, cats, dogs, and horses. Eating large amounts can cause vomiting, diarrhoea, weakness, and confusion. Its sap can irritate skin and eyes. The supplied edible-use claims derive from another species, not this one.