Cuscuta

This article is about the plant. For the waterway, see River Dodder.

Cuscuta
Cuscuta europaea on Sambucus ebulus
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Solanales
Family:	Convolvulaceae
Genus:	Cuscuta L.
Species
About 100-170 species, including: Cuscuta approximata Cuscuta californica Cuscuta epithymum Cuscuta europaea Cuscuta pentagona Cuscuta salina

Cuscuta (Dodder) is a genus of about 100-170 species of yellow, orange or red (rarely green) parasitic plants. Formerly treated as the only genus in the family Cuscutaceae, recent genetic research by the Angiosperm Phylogeny Group has shown that it is correctly placed in the morning glory family, Convolvulaceae. 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.

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

Cuscuta europaea in flower

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

Cuscuta on acacia tree in Punjab India

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 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, lespedeza, flax, clover, potatoes, chrysanthemum, dahlia, helenium, trumpet vine, ivy and petunias, 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 viral 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 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

This dodder is engulfing a sage in the Mojave Desert.

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 such as Dacthal in the spring. Examples of non-host crops include grasses and many other monocotyledons. 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.

Selected species

• Cuscuta americana
• Cuscuta applanata
• Cuscuta approximata Bab. - Alfalfa dodder (Eurasia, Africa)
• Cuscuta attenuata
• Cuscuta australis
• Cuscuta boldinghii
• Cuscuta brachycalyx
• Cuscuta californica Hook. & Arn. - California dodder (western North America)
• Cuscuta campestris
• Cuscuta cassytoides
• Cuscuta ceanothi
• Cuscuta cephalanthi
• Cuscuta chinensis
• Cuscuta compacta
• Cuscuta coryli
• Cuscuta corylii
• Cuscuta cuspidata
• Cuscuta decipiens
• Cuscuta dentatasquamata
• Cuscuta denticulata
• Cuscuta epilinum
• Cuscuta epithymum - Clover dodder (Eurasia, Africa)
• Cuscuta erosa
• Cuscuta europaea - Greater Dodder (Europe)
• Cuscuta exaltata
• Cuscuta fasciculata
• Cuscuta gigantea
• Cuscuta globulosa
• Cuscuta glomerata
• Cuscuta gronovii

• Cuscuta harperi
• Cuscuta howelliana
• Cuscuta indecora
• Cuscuta indesora
• Cuscuta japonica
• Cuscuta jepsoni
• Cuscuta leptantha
• Cuscuta lupuliformis
• Cuscuta macrolepis
• Cuscuta megalocarpa
• Cuscuta monogyna
• Cuscuta mitriformis
• Cuscuta obtusiflora
• Cuscuta odontolepis
• Cuscuta pacifica - Salt Marsh Dodder (British Columbia, Baja California, United States)
• Cuscuta pentagona - Golden Dodder (United States)
• Cuscuta plattensis
• Cuscuta polygonorum
• Cuscuta potosina
• Cuscuta reflexa
• Cuscuta rostrata
• Cuscuta runyonii
• Cuscuta salina Engelm. - "Salt marsh" dodder (western United States)
• Cuscuta sandwichiana Choisy- Kaunaʻoa (Hawaiʻi)
• Cuscuta squamata
• Cuscuta suaveolens
• Cuscuta suksdorfii
• Cuscuta tuberculata
• Cuscuta umbellata
• Cuscuta vivipara
• Cuscuta warneri

Uses

The petroleum ether extract of C. reflexa may be useful in treatment of androgen induced alopecia by inhibiting the enzyme 5alpha-reductase.

C. chinensis seeds (Chinese=Tu-Si-Zi) have long been used for the treatment of osteoporosis in China and some Asian countries. Kaempferol and hyperoside may be the active compounds that have osteogenic effect.

C. chinensis is a commonly used traditional Chinese medicine to nourish the energetic liver and kidney matrices.

Gallery

• 
  Cuscuta with a gall, Spinnerstown, Bucks County, Pennsylvania, USA August, 2010
• 
  Cuscuta flowers, Spinnerstown, Bucks County, Pennsylvania, USA August, 2010
• 
  Cuscuta sp., Garden of the Gods Wilderness, Shawnee National Forest, South Illinois, USA, 2000
• 
  Cuscuta sp., Garden of the Gods Wilderness, Shawnee National Forest, South Illinois, USA, 2000

Further reading

• Everitt, J.H. (2007). Weeds in South Texas and Northern Mexico. Lubbock: Texas Tech University Press. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help) ISBN 0-89672-614-2
• Haupt, S. (2001). "Macromolecular trafficking between Nicotiana tabacum and the holoparasite Cuscuta reflexa". Journal of Experimental Botany. 52 (354): 173–177. doi:10.1093/jexbot/52.354.173. ISSN 1460-2431.
• Machado, M.A.; Zetsche, K. (1990). "A structural, functional and molecular analysis of plastids of the holoparasites Cuscuta reflexa and Cuscuta europaea". Planta. 181 (1). doi:10.1007/BF00202329. ISSN 0032-0935.
• Hibberd, J. M.; Bungard, R. A.; Press, M. C.; Jeschke, W. D.; Scholes, J. D.; Quick, W. P. (1998). "Localization of photosynthetic metabolism in the parasitic angiosperm Cuscuta reflexa". Planta. 205 (4): 506–513. doi:10.1007/s004250050349. ISSN 0032-0935.

External links

• Costea, M. 2007-onwards. Digital Atlas of Cuscuta (Convolvulaceae)
• Cuscuta on National Public Radio
• 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
• Common Scents: Plants Constantly Catch a Whiff of Their Neighbors' Perfume "parasitic dodder vine sniffs out healthy hosts"