- Sale!Milkweed aka Asclepias is a herbaceous perennial flowering plant named for its milky latex substance for cardiac glycosides. Found in south Florida near the Everglades and Miami Dade County. Monarch caterpillars eat milkweed. In fact, the monarch butterfly is also known as the “milkweed butterfly.” The milkweed plant provides all the nourishment the monarch needs to transform the Monarch caterpillar into the adult butterfly. But these plants are rapidly disappearing, due to the loss of habitat stemming from land development and the widespread spraying of weed killer on the fields where they live.