Light micrograph of a section through a haustorium 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. Once inside, it 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.