762 Cuscuta spp.Common Names: dodder, lovevine, strangleweed, hellbind, goldthread, devil Family: Convolvulaceae (morning glory Family)
Dodder is a parasitic vine with smooth, wiry, twining stems that attach to a host plant with tiny suckers. Only the seedlings have roots. The tangled stems are usually orange, but may be yellowish, whitish, or greenish or even tinged with red or purple. The stems turn black when the plant dies. One dodder plant looks like a fat yellow thread tangled in the weeds. Large numbers of them crawl over shrubbery to form blankets that look like masses of wet excelsior. The tiny leaves are scalelike and almost invisible, whereas the numerous clusters of little waxy cream colored 5-petaled flowers and subsequent 1/8 in (0.3 cm) seedpods are more noticeable. There are 2 to 4 3-sided brownish seeds in each 2-celled capsule.
Botanists recognize some 150 species of dodder, though some authorities split out a few of them into the genus Grammica. Dodder species cannot be identified until they develop mature flowers and most people can't tell them apart even then. However it is possible to distinguish dodder from the vegetatively similar, but unrelated, love vine (Cassytha filiformis), which is also a parasitic vine that sprawls over its host with twining yellowish stems. Cassytha (which is in the laurel family, Lauraceae) has a spicy odor and inconspicuous, petal-less greenish-white flowers that produce 5-7 mm white berrylike drupes.
There are Cuscuta species native to most every part of the temperate and tropical world. Habitat varies with the host plant, but they generally parasitize plants that grow in disturbed areas.
CultureDodder is usually regarded as an annual, but it may be perennial in warm climates. Some species are salt tolerant and/or pesticide resistant. Dodder is itself parasitized by a fungus, Colletotrichum destructivum. Light: Dodders seem to grow most vigorously in full sun. Moisture: Moisture requirements vary according to host plant. Some species grow in marshes, others in arid brushlands. Hardiness: USDA Zones 4 - 11. Propagation: Dodder reproduces readily from seed. A single plant may produce thousands of seeds, which can remain viable in the soil for many years. Dodder seeds are often inadvertently harvested, distributed, and planted along with host plant seeds. They may also be spread in hay, soil, water, or animal manure. If you actually want to grow this plant, harvest the seed as soon as they ripen in the fall and either plant them in the soil at the base of an appropriate host plant or wedge them into its stem forks and crevices. Broken stems will readily attach to new hosts.
Various dodder species have been used to treat a great variety of different ailments in numerous cultures. Some are thought to take on and enhance the medicinal properties of the plants they parasitize. The dodder that grows on thyme (Cuscuta epithymum) has been a favorite in European folk medicine. The following species are also frequently mentioned as medicinal herbs: C. americana, C. chinensis, C. europaea, C. japonica, C. megalocarpa, and C. reflexa.
If you are a horror movie producer looking for inspiration, this could be your plant! It has it all: long orange tentacles to grasp and entangle its victims, suckers to drain their life juices, and a devastating lifestyle to match that of any hostile alien symbiont. Different species parasitize different host plants. Some are very selective, whereas others can grow on a variety of herbaceous weeds. But even this villain has a few good points: Certain species grow on even more obnoxious weeds and may thus have promise for biocontrol use. Cuscuta japonica, for example, grows on kudzu! Dodder has also been identified as in important foodplant for the western elfin butterfly (Incisalia augustinus).
For obvious reasons, the USDA classifies dozens of dodder species as Noxious Weeds. American dodder (C. americana) and golden dodder (C. campestrisis) are particularly damaging agricultural weeds. Dodder is a major economic problem for such crops as alfalfa, clover, and flax. Other plants commonly parasitized by dodder include many daisy relatives (especially chrysanthemums), Virginia creepers, trumpet vines, petunias, camellias, citrus, buttonbushes, cucumbers, potatoes, tomatoes, coleus, impatiens, and various legumes. Dodder can also carry plant viruses, including Phytoplasma, which is responsible for many of the "yellows" diseases. Although dodder is not thought of as a poisonous plant, cows and horses have shown colicky symptoms after eating it.
So how do you get rid of the evil stuff? It isn't easy. If dodder is growing on and among plants you cherish, all you can do is try to pull it from all affected parts of the host plants. Take care to get every fragment of dodder, then incinerate the dodder-infested plant remains. This should be done before the dodder begins to go to seed. If you have a really awful infestation or find it growing on plants you are willing to sacrifice, you can use a pre-emergent herbicide in the early spring or apply 2,4-D to kill both dodder and host plant. Burning will kill the plants and seeds, but buried seeds will then germinate. Don't go off on a knee-jerk search-and-destroy mission every time you see a strand of dodder in the bushes, though. Many dodders require very specific host plants and are therefore rare species themselves. If a dodder is in your garden or growing nearby among the weeds in a disturbed area, go after it with a vengeance. But if the dodder is in a natural habitat growing on native vegetation, stop and think first. Watch it for awhile. If it seems be relying on just one or two kinds of plants and not attacking others or moving into cultivated areas, let it be. Who knows what that species of dodder might turn out to be the cure for?
Steve Christman 7/28/00; updated 10/29/04