Butterfly Milkweed (Asclepias tuberosa) can be found growing wild in upland areas around Tucson, but these plants are far more commonly found growing in our local gardens. Butterfly Milkweeds have brilliantly colored flowers, an attractive form, and are quite easy to grow.
Like other milkweeds, Butterfly Milkweeds are poisonous and contain cardiac glycosides which can cause lethargy, weakness, bloating, inability to stand upright, elevated body temperature, rapid and weak pulse, difficulty in breathing, spasms, dilated pupils, and coma if eaten by humans or animals.
Monarch Butterflies (Danaus plexippus) lay their eggs on Butterfly Milkweed, and the larva consume the foliage. Monarch Butterfly caterpillars are not harmed by the toxic cardiac glycosides, instead they retain them, and these foul-tasting toxins protect both the poisonous caterpillars and adult Monarch Butterflies from hungry birds. Birds learn to avoid any butterfly with the Monarch Butterfly's orange, black, and white coloration pattern.