Cuscuta is a genus of about 100-170 species of yellow, orange or red (rarely green) parasitic plant

Parasitic plant

A parasitic plant is one that derives some or all of its sustenance from another plant. About 4,100 species in approximately 19 families of flowering plants are known. Parasitic plants have a modified root, the haustorium, that penetrates the host plant and connects to the xylem, phloem, or...

s. Formerly treated as the only genus in the family Cuscutaceae, recent genetic research by the Angiosperm Phylogeny Group

Angiosperm Phylogeny Group

The Angiosperm Phylogeny Group, or APG, refers to an informal international group of systematic botanists who came together to try to establish a consensus on the taxonomy of flowering plants that would reflect new knowledge about plant relationships discovered through phylogenetic studies., three...

 has shown that it is correctly placed in the morning glory

Morning glory

Morning glory is a common name for over 1,000 species of flowering plants in the family Convolvulaceae, whose current taxonomy and systematics is in flux...

 family, Convolvulaceae

Convolvulaceae

Convolvulaceae, known commonly as the bindweed or morning glory family, are a group of about 60 genera and more than 1,650 species of mostly herbaceous vines, but also trees, shrubs and herbs.- Description :...

. The genus is found throughout the temperate to tropical regions of the world, with the greatest species diversity in subtropical and tropical regions; the genus becomes rare in cool temperate climates, with only four species native to northern Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

.

Old folk names include devil's guts, devil's hair, devil's ringlet, goldthread, hailweed, hairweed, hellbine, love vine, pull-down, strangleweed, angel hair, and witch's hair.

Appearance

Dodder can be identified by its thin stems appearing leafless, with the leaves

Leaf

A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....

 reduced to minute scales. From mid-summer to early autumn, the vines can produce small fruit that take the same color as the vine, and are approximately the size of a common pea. It has very low levels of chlorophyll

Chlorophyll

Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...

; some species such as Cuscuta reflexa can photosynthesize slightly, while others such as C. europaea are entirely dependent on the host plants for nutrition.

Dodder flower

Flower

A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s range in color from white to pink to yellow to cream. Some flower in the early summer, others later, depending on the species. The seed

Seed

A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

s are minute and produced in large quantities. They have a hard coating, and can survive in the soil for 5–10 years or more.

Dodder seeds sprout at or near the surface of the soil. While dodder germination

Germination

Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

 can occur without a host, it has to reach a green plant quickly; dodder grows toward the smell of nearby plants. If a plant is not reached within 5 to 10 days of germination, the dodder seedling will die. Before a host plant is reached, the dodder, as other plants, relies on food reserves in the embryo; the cotyledons, though present, are vestigial.

Parasitism

After a dodder attaches itself to a plant, it wraps itself around it. If the host contains food beneficial to dodder, the dodder produces haustoria that insert themselves into the vascular system of the host. The original root of the dodder in the soil then dies. The dodder can grow and attach itself to multiple plants. In tropical areas it can grow more or less continuously, and may reach high into the canopy of shrubs and trees; in temperate regions it is an annual plant

Annual plant

An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...

 and is restricted to relatively low vegetation that can be reached by new seedlings each spring.

Dodder is parasitic on a very wide variety of plants, including a number of agricultural and horticultural crop species, such as alfalfa

Alfalfa

Alfalfa is a flowering plant in the pea family Fabaceae cultivated as an important forage crop in the US, Canada, Argentina, France, Australia, the Middle East, South Africa, and many other countries. It is known as lucerne in the UK, France, Australia, South Africa and New Zealand, and known as...

, lespedeza

Lespedeza

Lespedeza is a genus of some 40 species of flowering plants in the pea family , commonly known as bush clovers or Japanese clovers...

, flax

Flax

Flax is a member of the genus Linum in the family Linaceae. It is native to the region extending from the eastern Mediterranean to India and was probably first domesticated in the Fertile Crescent...

, clover

Clover

Clover , or trefoil, is a genus of about 300 species of plants in the leguminous pea family Fabaceae. The genus has a cosmopolitan distribution; the highest diversity is found in the temperate Northern Hemisphere, but many species also occur in South America and Africa, including at high altitudes...

, potato

Potato

The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...

es, chrysanthemum

Chrysanthemum

Chrysanthemums, often called mums or chrysanths, are of the genus constituting approximately 30 species of perennial flowering plants in the family Asteraceae which is native to Asia and northeastern Europe.-Etymology:...

, dahlia

Dahlia

Dahlia is a genus of bushy, tuberous, perennial plants native to Mexico, Central America, and Colombia. There are at least 36 species of dahlia, some like D. imperialis up to 10 metres tall. Dahlia hybrids are commonly grown as garden plants...

, helenium

Helenium

Helenium is a genus of about 40 herbaceous flowering plants in the daisy family Asteraceae, native to North America and Central America. They bear yellow or orange daisy-like flowers...

, trumpet vine

Trumpet vine

The trumpet vine or trumpet creeper , also known as "cow itch vine" and as "hummingbird vine", is a large and vigorous woody vine of the family Bignoniaceae, notable for its showy trumpet-shaped flowers...

, ivy

Ivy

Ivy, plural ivies is a genus of 12–15 species of evergreen climbing or ground-creeping woody plants in the family Araliaceae, native to western, central and southern Europe, Macaronesia, northwestern Africa and across central-southern Asia east to Japan and Taiwan.-Description:On level ground they...

 and petunia

Petunia

Petunia is a widely cultivated genus of flowering plants of South American origin, closely related with tobacco, cape gooseberries, tomatoes, deadly nightshades, potatoes and chili peppers; in the family Solanaceae. The popular flower derived its name from French, which took the word petun, meaning...

s, among others.

Dodder ranges in severity based on its species and the species of the host, the time of attack, and whether any viruses are also present in the host plant. By debilitating the host plant, dodder decreases the ability of plants to resist virus diseases, and dodder can also spread plant diseases from one host to another if it is attached to more than one plant.

Host finding

A report published in Science (Vol 313; Sept. 29, 2006) by Runyon, Mescher, and De Moraes, researchers at Penn State University, demonstrates that dodder use airborne volatile organic compound

Volatile organic compound

Volatile organic compounds are organic chemicals that have a high vapor pressure at ordinary, room-temperature conditions. Their high vapor pressure results from a low boiling point, which causes large numbers of molecules to evaporate or sublimate from the liquid or solid form of the compound and...

 cues to locate their host plants. Seedlings of Cuscuta pentagona exhibit positive growth responses to volatiles released by tomato and other species of host plants. When given a choice between volatiles released by the preferred host tomato and the non-host wheat, the parasite exhibited preferential growth toward the former. Further experiments demonstrated attraction to a number of individual compounds released by host plants and repellance by one compound released by wheat. These results do not rule out the possibility that other cues (e.g., light) may also play a role in host location.

Prevention and treatment

Many countries have laws prohibiting import of dodder seed, requiring crop seeds to be free of dodder seed contamination. Before planting, all clothes should be inspected for dodder seed when moving from an infested area to a non-infested crop. When dealing with an infested area, swift action is necessary. Recommendations include planting a non-host crop for several years after the infestation, pulling up host crops immediately, particularly before the dodder produces seed, and use of preemergent herbicides

Preemergent herbicides

Preemergent herbicides prevent the germination of seeds by inhibiting a key enzyme. In some areas of the world, preemergent herbicides are used to prevent crabgrass from appearing in summer lawns.-Brands:-Crabgrass:...

 like Dacthal in the spring. Examples of non-host crops include grass

Grass

Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

es and many other monocotyledon

Monocotyledon

Monocotyledons, also known as monocots, are one of two major groups of flowering plants that are traditionally recognized, the other being dicotyledons, or dicots. Monocot seedlings typically have one cotyledon , in contrast to the two cotyledons typical of dicots...

s. If dodder is found before it chokes a host plant, it may be simply removed from the soil. If choking has begun, the host plant must be pruned significantly lower than the dodder, as dodder is versatile and can grow back if present from haustoria.

Uses

The petroleum ether

Petroleum ether

Petroleum ether, also known as benzine, VM&P Naphtha, Petroleum Naphtha, Naphtha ASTM, Petroleum Spirits, X4 or Ligroin, is a group of various volatile, highly flammable, liquid hydrocarbon mixtures used chiefly as nonpolar solvents...

 extract of C. reflexa may be useful in treatment of androgen

Androgen

Androgen, also called androgenic hormone or testoid, is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of male characteristics in vertebrates by binding to androgen receptors...

 induced alopecia

Alopecia

Alopecia means loss of hair from the head or body. Alopecia can mean baldness, a term generally reserved for pattern alopecia or androgenic alopecia. Compulsive pulling of hair can also produce hair loss. Hairstyling routines such as tight ponytails or braids may induce Traction alopecia. Both...

 by inhibiting the enzyme 5alpha-reductase.

C. Chinensis seeds (Chinese=Tu-Si-Zi) have long been used for the treatment of osteoporosis

Osteoporosis

Osteoporosis is a disease of bones that leads to an increased risk of fracture. In osteoporosis the bone mineral density is reduced, bone microarchitecture is deteriorating, and the amount and variety of proteins in bone is altered...

 in China and some Asian countries.Kaempferol

Kaempferol

Kaempferol is a natural flavonol, a type of flavonoid, that has been isolated from tea, broccoli, Delphinium, Witch-hazel, grapefruit,cabbage, kale, beans, endive, leek, tomato, strawberries, grapes, brussels sprouts, apples and other plant sources. Kaempferol is a yellow crystalline solid with a...

 and hyperoside

Hyperoside

Hyperoside is a chemical compound. It is the 3-O-galactoside of quercetin. It is a medicinally active compound that can be isolated from Drosera rotundifolia, from the Stachys plant, from Prunella vulgaris, from Rumex acetosella, Cuscuta Chinensis seeds and from St John's wort.In Rheum nobile and R...

 may be the active compounds that have osteogenic effect.

C. Chinensis is a commonly used traditional Chinese medicine to nourish the liver and kidney.

External links

• Costea, M. 2007-onwards. Digital Atlas of Cuscuta (Convolvulaceae)
• Flora of China: Cuscuta
• Lanini, W. T., et al. Dodder. Pest Notes Jan 2002: 1-3. 15 July 2005. Online (pdf file).
• Swift, C. E. Cuscuta and Grammica species - Dodder: A Plant Parasite. Colorado State University Cooperative Extension. Online.
• Dodder (Cuscuta species). Weed Listings. 2005. Online.
• Medicinal uses of Cuscuta in Armenia