Dodder is our only economically important parasitic plant. It is an annual with a colorless flower which produces very small, light seed. It tolerates wet sites so the seed often gets into irrigation water and is carried to the fields. A problem in ornamental flowers such as petunia and geranium. It is a serious problem in blueberries. Each species has its own host. The dodder plant is yellow because it has no chlorophyll which means it cannot produce its own food. So it penetrates the desirable plant with haustoria and derives its food from the host plant.