Common Milkweed, Asclepias syriaca
Common Milkweed is the plant that most people think of when they hear the term "milkweed." Milkweed are herbaceous, perennial wildflowers that get their name from the milky sap they produce. This species grows 3-5 feet tall and forms large balls of purplish to pink flowers that bloom May-August. Common Milkweed grows best in direct sunlight and in medium to fine sandy, rocky, or calcareous soils in a variety of disturbed sites. It can be found in open fields, croplands, meadows, roadsides, along fence rows, and in pastures.
As the only host plant for the monarch butterfly, milkweed plays an essential role in the butterfly's life cycle. The milky sap in the leaves contains cardiac glycosides. After the monarch caterpillars ingest the sap they become mildly poisonous and have a bitter flavor that protects them from predators. Milkweed also serves as a host plant for the milkweed tussock moth and several other species of moths and butterflies. It provides nectar to a large variety of other pollinators as well.