Common Milkweed (Asclepias syriaca) is a handsome, straight plant you see in every farm field and growing wherever a roadside hasn't been mowed. Leaves are glossy and thick, and the blooms are large, rounded clusters of purplish/pink flowers atop plants that range from 2 to 5 ft. It's native in the US from Canada to Georgia, and west to Texas.
The botanical name, "Asclepias"; is after Aesclepios, the Greek God of medicine, since this plant has been used as a medicinal since ancient times. "Milkweed" derives from the fact that when you break a stem, sticky white sap immediately appears. Common Milkweed is one of our commonest "weeds," but one almost all wildflower gardeners want.
This is the plant famous for its "silky seeds" in fall when you see the drying cone-shaped seedpods crack open and their snow-white shiny fluff flying around the meadow. This is the dispersal mechanism for the large shiny seeds of common milkweed. Every kid loves to blow them away in fall, like dandelion seeds in spring.
Even though farmers hate milkweed, you'll love it in your wildflower garden...for two reasons. It's beautiful and dependably perennial, and it's the No. 1 plant visited by Monarch butterflies on their famous migration south every summer and fall.
In fact, during late summer, it's somewhat rare to see a milkweed plant without a monarch perched upon the flowers, making it the No. 1 butterfly magnet among our wildflowers. ("Butterfly Weed" is a close relative, with bright orange flowers.)