365 Urban Species. #109: Giant Milkweed

[urbpan]

Urban species # 109: Giant milkweed Calotropis procera
Photos by cottonmanifesto

Along the road to my in-laws' house are large weeds with round, opposite leaves. In some places they are big enough to be called shrubs; in others they can only be called trees. They have attractive, purple, star-shaped flowers, that remind me of the tiny flowers of black swallow-wort, an invasive climbing milkweed. When we looked at them closely we found yellow aphids, tended by ants. The only place I have seen yellow aphids before is on common milkweed plants.

I suspected, given these clues, that the plant was a kind of milkweed. The fact that milkweeds are poisonous, and that all the wild plants in Antigua have to be goat-resistant in some way helped reinforce this suspicion. When I got home, research bore this out.

Native to India and Africa, giant milkweed has a history of various uses, mainly medicinal. Studies in the new world have shown that it is useful as a food plant for monarch butterfly caterpillars. Why it was brought to Antigua is anyone's guess, but it has become one of the most common waste area weeds on the island.