Dodders are unique plants in the genus Cuscuta Linnaeus. Some authorities place the genus as members of the Convolvulaceae, the morning glory family; other taxonomists feel these odd plants deserve their own family, the Cuscutaceae. There are nine species in Florida, about fifty native and introduced species in North America, and 150 to 170 species worldwide.

Dodders are parasitic plants. Some species are capable of a little photosynthesis and are properly known as hemiparasites, but most dodders cannot photosynthesize and must receive all their food and water from a host. These dodders are holoparasites. Some are generalists and will parasitize any plant; others are host-specific and only survive by 'theft' from certain plants. Most dodders are annuals, but a few species can survive winter inside their hosts and regenerate their vines in spring. ("Convolvulaceae Juss." College of Science, Southern Illinois University-Carbondale)

The dodder embryo is coiled inside the seed and protected by a hard seed coat. Like other seeds, when dodder germinates it sends a radicle, the first embryonic root into the soil. The embryo elongates and the tiny leafless vine begins circumnutating, moving through 360 degrees, in a counterclockwise direction.

The vine is sensitive to touch. During its motion when it hits anything, it begins twining about that object. Without a host, a dodder seedling has about a ten day lifespan, but odds are that a few seedlings will be fortunate enough to twine about a host.

Once dodder has wrapped around a host, the side of the vine in contact with the host produces specialized adventitious roots called haustoria. A haustorium grows into the host until it contacts the phloem and xylem tissues. The haustorium diverts the host's water, sugars, and other photosynthates. Once connected to its host, the portion of the vine between the contact point and the soil dies. The dodder is then dependent on its host. ("Background on the genus Cuscuta (dodders)", Colin Purrington, Swarthmore College, 2001)

Dodder usually does not kill its host, but it weakens the plant. Note that the Ludwigia has healthy leaves below the dodder's contact and brown or yellowing leaves above the contact points. Depending upon the species, dodder produces tiny, 2 to 4 millimeter, white or pink flowers in dense cymes. The inflorescence is usually close to a contact point. Most dodders are yellow or orange and the only way to determine the species is to examine the tiny flowers under magnification.