Monarch Butterflies are declining rapidly as a species—by a staggering 90 percent in the past two decades. Butterfly milkweed, an easy-to-grow perennial characterized by attractive foliage and bright orange flowers; it is also the only plant fledgling Monarch caterpillars feed on. People can provide important habitat for them in home landscaping—just by cultivating some milkweed for the caterpillars to feed on.