Common milkweed

Ozone injury usually appears as black or purple spots (stipple), yellow or white bleached spots (chlorotic mottle, needle tip burn), or leaf browning (necrosis). Ozone may also cause premature leaf drop (senescence).

Healthy Common milkweed Plant Courtesy, USDA PLANTS Database

Close-Up of Healthy Common milkweed flowers Courtesy, USDA PLANTS Database

Ozone Injury to Common milkweed Leaf Courtesy, Ozone Biomonitoring Program

Ozone Injury to Common milkweed Leaf Courtesy, Ozone Biomonitoring Program