Milkweeds (so named for their milky sap) are the best-known representatives of this group of plants. Bloom in summer, typically bearing many small, starlike flowers in broad, flattened clusters at branch tips. All have inflated seedpods with silky seeds. Just a few species are cultivated in gardens.Asclepias speciosa
Native to western and central North America. This striking perennial grows 2–4 ft. tall and not quite as wide; may spread by underground stems to form colonies. Thick, upright stems hold big, softly hairy leaves of gray; summer flowers are 3-in.-wide balls of fragrant, purplish pink. Long winter dormancy; new shoots may not appear until midspring. Needs only occasional water once established.
Grows to 7 ft. tall, 1 1/2–2 1/2 ft. wide, with yellow-centered, yellow or orange-yellow single ...
Mounding growth to 6–12 in. high and 1 1/2–3 ft. wide. Lacy, silvery blue foliage; flowers...
From southern Arizona, northern Mexico. To 1 1/2–2 1/2 ft. tall and 1 1/2 ft. wide, with narrow,...