Nicandra physalodes

Native from Peru to northwestern Argentina, this annual herb reaches about 2 to 5 feet tall. It has escaped cultivation and become naturalized across large areas of the United States. Each pale blue to lavender flower lasts only a day, but the plant produces a succession of blooms that attract bees. The fruits develop inside enlarged, papery calyces, and the plant spreads by reseeding. Its foliage is toxic. Photographed in Colombia.