Light micrograph of a section through some haustoria of a parasitic dodder plant (Cuscuta sp.). A haustorium is a modified root of a parasitic plant, which penetrates the tissues of its host plant. The host plant stem is blue and purple here, with the dodder stem orange, and the haustoria punching in to the host's wall. Once inside, the haustoria sucks sugars from the host's phloem tissues, and water and minerals from the xylem. Dodder is a widespread parasitic plant that attacks a huge variety of plants, including crops. It derives all its nutrients from the host. It is an annual in temperate regions but can grow year-round in tropical areas. Importing it is illegal in many areas, and batches of seed are checked for contamination by its own seeds.