Fact Sheets


Cuscuta L. spp.

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Common Name(s) :

Nom(s) commun(s) :

(English) (GC 2016; USDA-ARS 2022)

Love-tangle (English) (Darbyshire 2003)

Coral-vine (English) (Darbyshire 2003)

Cuscutes (French) (GC 2016)

Cuscute (French) (Darbyshire 2003)

tu si zi shu 菟丝子属 (Chinese) (eFloras 2022)

  • Field dodder (Cuscuta campestris) seeds

  • Field dodder (Cuscuta campestris) seed

  • Field dodder (Cuscuta campestris) seeds

  • Field dodder (Cuscuta campestris) seed

  • Cuscuta gronovii 

  • Cuscuta gronovii 

  • Cuscuta gronovii 

  • Big fruit dodder (Cuscuta megalocarpa) seeds

  • Big fruit dodder (Cuscuta megalocarpa) seed

  • Big fruit dodder (Cuscuta megalocarpa) seed

  • Cuscuta megalocarpa (big fruit dodder) capsule

  • Field dodder (Cuscuta pentagona) seeds

  • Field dodder (Cuscuta pentagona) seed

  • Field dodder (Cuscuta pentagona) seed

  • Cuscuta pentagona capsules

  • Cuscuta salina

  • Cuscuta salina

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Regulation :

Remarques Réglementation:

  • CFIA Weed Seeds Order - Class 1: Prohibited Noxious Weed Seeds
  • List of Pests Regulated by Canada
  • ​Quarantine lists of countries e.g. China *may be updated without notice
  • Quarantine lists of countries e.g. Mexico *may be updated without notice
  • USA Federal Noxious Weed Seed List

Regulation Notes:

  • Prohibited Noxious, Class 1 in the Canadian Weed Seeds Order (2016) under the Seeds Act. All imported and domestic seed must be free of Prohibited Noxious weed seeds.
  • Listed on the List of Pests Regulated by Canada established under the Plant Protection Act. (Exception of: Cuscuta campestris, C. cephalanthi, C. coryli, C. gronovii, C. indecora, C. pacifica, C. pentagona, C. polygonorum and C. umbrosa)

Distribution :

Répartition :

The Cuscuta genus contains 194 species and grows nearly worldwide with the majority of species (approximately 75%) native to North and South America, and a small number (15-20 species) distributed worldwide as agricultural and horticultural pests (Costea et al. 2015). The genus includes 50 species found in the United States and 12 species found in Canada, distributed across all provinces except the Northwest Territories, Nunavut and Yukon Territory (Brouillet et al. 2010+; USDA-NRCS. 2022).

Habitat and Crop Association :

Habitat et Cultures Associées :

Cuscuta species occupy a wide variety of habitats in temperate and tropical regions, including desert and riparian areas, littoral zones, high mountains, grasslands, forests, and saline and disturbed habitats (Costea et al. 2015).

Many Cuscuta species parasitize a wide range of host species from different plant families. It was found that Medicago sativa (alfalfa) and Trifolium species (clovers) are the crops most commonly contaminated by Cuscuta species (Lanini and Kogan 2005). Cuscuta rarely parasitizes plants with woody stems or monocotyledonous species (e.g., from the Poaceae, Cyperaceae, Liliaceae, Iridaceae, etc.), but Allium cepa (onion), Allium sativum (garlic) and Asparagus officinalis (asparagus) crops can be infested (Lanini and Kogan 2005).


Economic Use, cultivation area, and Weed Association :

Utilisation économique, zone de culture et association de mauvaises herbes :

Duration of Life Cycle :

Durée du cycle vital:


Dispersal Unit Type :

Type d’unité de dispersion :

Seed or capsules

General Information


Like other parasitic plants, Cuscuta species can act as keystone species in natural (i.e. non-agricultural) ecosystems (Press and Phoenix 2005; Costea et al. 2015). The parasite changes resource allocation, growth, competition and reproduction of the host plant; an infestation can change the structure and population dynamics of a plant community including herbivores and pollinators (Press and Phoenix 2005).

C. campestris is a generalist weed of 25 crop species in over 55 countries, parasitizing vegetables, fruits, woody plants, ornamental species, and commonly contaminates small-seeded legumes (Lanini and Kogan 2005; Costea and Tardiff 2006). Other species may have a narrow range of crop hosts: C. epithymum in Trifolium species (clovers), C. epilinum in Linum usitatissimum (flax) and C. gronovii in Vaccinium macrocarpon (cranberries), Vitis species (grapevine) and Ruta species (citrus) (Costea and Tardiff 2006). The seed of certain Cuscuta species are used in Traditional Chinese Medicine, specifically C. chinensis, C. australis and C. japonica (Zhao and Yang 2017). The plants of Cuscuta have been used medicinally, as sources of dye, as an antifungal, insecticide, and are also suspected of being toxic to humans, livestock and other animals (Costea and Tardiff 2006).

Cuscuta species plants have the capacity to produce many seeds, e.g. C. campestris can produce 16,000 seeds per plant (Costea and Tardiff 2006). Cuscuta species seeds have remained viable in the field for up to 10 years, and species such as C. pentagona have been found to be viable in dry storage for up to 51 years (Costea and Tardiff 2006).

Cuscuta species are dispersed over long distances primarily in contaminated crop seed (Costea and Tardiff 2006). Seeds of Cuscuta species are heavier than other parasitic species (i.e. Striga species and Orobanche species), and are likely not wind dispersed (Costea et al. 2006a). The seeds and capsules can float, and may be locally dispersed by flowing water (Costea et al. 2006a). Seeds can produce mucilage (except in subgenus Monogynella), adhering to birds and farm machinery for longer distance dispersal (Olszewski et al. 2020). Cuscuta plants can reproduce vegetatively by regenerating from broken fragments, and the host-parasite connector (haustoria) may overwinter in the tissue of plant hosts (Costea and Tardiff 2006).



Cuscuta spp. infestation (Jennifer Olson, Oklahoma State University, Bugwood.org)



  • Capsule


    • Capsule length size range: 1.3 – 6.5 mm, width: 1.6 – 5 mm (Costea and Tardiff 2006)


    • Generally globose, compressed at both ends, but may be oval or cone-shaped in some species (Costea and Tardiff 2006)

    Surface Texture

    • Smooth


    • Straw yellow

    Other Features

    • Cuscuta species are generally encountered as loose seeds, but intact capsules with seed inside may be found contaminating seeds or grains after processing
    • Capsule is 2-chambered, with 1 or 2 seeds per chamber (Costea and Tardiff 2006; eFloras 2017)
    • Capsules may remain closed (indehiscent) or open to release the seeds (dehiscent), opening by an irregular split in the capsule or by a seam around the capsule (Costea and Tardiff 2006)
    • Capsules have a persistent perianth at the base, and a hole at the top where the styles were attached during flowering (Costea and Tardiff 2006)
  • Seed


    Seeds of Cuscuta species are relatively small compared to other genera in the Convolvulaceae, but have a large size range within the genus. Seed size can be generally classified into the following three groups (subgenera) from Oleszewski et al. 2020:

    • Small-sized seeds in subgenus Cuscuta, length: 0.8-1.3 mm; width: 0.7-1.1 mm
    • Medium-sized seeds in subgenus Grammica, section Cleistogrammica: length, 1.0-1.6 mm; width: 1.0-1.4 mm
    • Large-sized seeds in subgenus Monogynella, length: 2.5-3.2 mm; width: 2.1-2.9 mm


    • Seeds are generally round or oval shaped, weakly trigonous, compressed or plano-convex in 3D

    Surface Texture

    • Seed surface texture varies from finely or coarsely granular, pitted, bubbled and scurfy
    • Surface texture of seeds is variable depending on species, seed maturity, or if moisture was absorbed during seed processing


    • Seed is generally yellow or orange coloured, but sometimes reddish or dark brown
    • Immature seed is white or light grey

    Other Features

    Hilum and hilum area

    • The hilum is within a larger round or oval area at or near one end of the seed, and is generally lighter or darker than the rest of the seed, generally marked with radiating striations
    • Hilum is a short, raised line in the middle of the hilum area
    • Hilum area size, colour, position, and the angle and length of the hilum may be features used in identification to the species level
    • The radicle may protrude as an umbo (bump) near the hilum

    Other than hilum

    • Immature seeds are generally white or light grey, with a smooth or wrinkled surface; interior of these seeds are hollow or soft textured
    • The seed coat contains starches and mucilage that can change the surface texture after wetting (Lyshede 1992; Olszewski et al. 2020)
  • Embryo


    • Embryo fills the seed


    • Embryo is linear curved, or irregularly coiled inside of the seed
    • The number of circular loops the embryo exhibits (described as ‘embryo coils’) can be used for species identification


    • Endosperm is translucent and hard, may be abundant in species such as C. pedicellata, and minimal in other species, (e.g. C. campestris) (Lyshede 1992)

    Other Features

    • Embryo lacks cotyledons (Costea et al. 2015)

Identification Tips


Seeds of Cuscuta species have features that distinguish them within the Convolvulaceae. These include:

• Small size (generally 1.0 mm diameter)
• Yellowish or orangish colour
• Round, plano-convex or weakly trigonous shape
• Bubbled, pitted, granular or scurfy surface texture
• Surface not tuberculate
• No hairs on the seed surface or around hilum

Pieces of inert material, e.g. stone cells, found in a sample may be mistaken for Cuscuta seeds, or the Cuscuta seeds may be confused for inert material. Close examination of the surface texture and the presence of a hilum area distinguish Cuscuta seeds from inert material.

Additional Botany Information



  • Flowers of Cuscuta species are small, and common species range from 2 – 4 mm (Costea and Tardiff 2006)
  • Flower consists of 4-5 petals, whitish with a membranous consistency; with fringed, scale-like structures that are unique to Cuscuta and likely have a protective role (Costea and Tardiff 2006)
  • Flowering is generally synchronous with the host in C. campestris and C. gronovii, or if the host plant has been weakened (Costea and Tardiff 2006)

Vegetative Features

  • Stems of Cuscuta are filamentous (hair-like), yellowish or orangish, long and twining around the host plant
  • Cuscuta plants are rootless and attached to the host by connectors (haustoria) that grow into the host plant tissues (Costea and Tardiff 2006)
  • Leaves have been reduced to small scales along the stem (Costea and Tardiff 2006)

Similar Species


Similar species are based on a study of seed morphology of various species, and those with similar dispersal units are identified. The study is limited by physical specimen and literature availability at the time of examination, and possibly impacted by the subjectivity of the authors based on their knowledge and experience. Providing similar species information for seed identification is to make users aware of similarities that could possibly result in misidentification.

Selected similar species of Cuscuta

Seeds of Cuscuta species have similar shape, hilum, colour and surface features and are generally difficult to distinguish to species. Closely related species have been grouped into subgenera, and further into clades within some subgenera (see Oleszewski et al. 2020). The size of the seed can be associated with size classes of subgenera and aid in identifying a seed to that level. Seed size is a readily viewable feature, and other microscopic features, such as the length of the hilum area and the number of times the embryo coils can be used to confirm the identity to the subgenus, clade or species level.

Features of Cuscuta species seed and capsules directly measured and from literature can be compared. Emphasis is on species that are regulated species, exceptions to quarantine species, encountered as a crop impurity and/or used medicinally. Measurements and feature description are from: Costea and Tardiff (2006a), Costea et al. (2006b, 2006c, 2009, 2011, 2015), and Oleszewski et al. (2020).

Seed length Seed width Capsule length Capsule width Hilum area length # of embryo coils
Subgenus Cuscuta
C. epithymum (L.) L. 0.9 mm 0.75 mm 1.6-2.2 mm 1.6-2.3 mm 0.1 mm 2
C. epilinum Weihe ex Boenn. 1.2 mm 1.1 mm 2.8-3.5 mm 3-4.2 mm 0.2 mm 2
C. europaea L. 1.3 mm 1.1 mm 0.3 mm 2
Subgenus Grammica
C. australis R. Br. 1.3 mm 1.2 mm 0.2 mm 2.5
C. campestris Yunck. 1.0-1.4 mm* 0.8-1.3 mm* 1.3-3 mm 1.9-3.5 mm 0.2 mm 2.5
1.12-1.54 mm 0.9-1.1 mm
1.2 mm 1.2 mm
C. cephalanthi Englm. 1.4 mm 1.3 mm 0.25 mm 3
C. chinensis Lam. 0.85 – 1.4 mm 0.8-1.2 mm 1.8-2.8 mm 0.8-2 mm
C. coryli Englm. 1.32-1.65 mm 1.25 – 4 mm 0.5 mm 2.5
1.8 mm 2.3 mm
C. gronovii Willd. 1.35 – 1.7 (-2.4) mm 1.2 – 1.5 (-1.6) mm 2.5-4.5 (-5.2) mm 2-4 (-5) mm 0.4 mm 3
1.8 mm 1.6 mm
C. indecora Choisy 1.4 – 1.9 mm 1.25 – 1.6 mm 0.4-0.5 mm 2.5
1.4 mm 1.5 mm
C. pacifica Costea & M. A. R. Wright 1.45–1.95 mm 1.25–1.43 mm 2–3.6 mm 1.4–2.1 mm 0.2 mm 3.5
1.4 mm 1.3 mm
C. pentagona Engelm. 0.9-1.1 mm 0.8-1 mm 0.2 mm 2.5
1.2 mm 1.1 mm
C. polygonorum Englm. 1.45 – 1.6 mm 1.25 – 1.39 mm 1.6 – 3 mm 2.5 – 5 mm 0.2 mm 3
1.1 mm 1.2 mm
C. umbrosa Beyr. ex Hook. (1.8-) 2 – 2.5 (-2.8) mm 1.5 – 1.65 mm 3.5 – 6.5 (-7) mm 3-5 (-6) mm 0.35 mm 3
2.0 mm 1.9 mm
Subgenus Monogynella
C. japonica Choisy 2.5 mm 2.1 mm 0.7 mm 2
C. reflexa Roxb. 3.2 mm 2.9 mm 0.8 mm 1
*Note: minimum and maximum of 20 seeds in a normal range of this species using image measurement (ISMA 2020)

Inert materials

There are many types of inert material that may have features similar to Cuscuta species seeds, e.g. small size, round shape, yellow colour, rough surface texture.
Inert materials that appear similar to dodder seeds may originate from: pieces of plant sap, stone cells from Solanum species fruit, or plant disease bodies. Under close examination, inert materials lack a hilum and are generally translucent.

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Brouillet, L., Coursol, F., Meades, S. J., Favreau, M., Anions, M., Bélisle, P. and Desmet, P. 2010+. VASCAN, the database of vascular plants of Canada. http://data.canadensys.net/vascan/ Accessed March 21, 2022.

Costea, M. and Tardif, F. J. 2006. The biology of Canadian weeds. 133. Cuscuta campestris Yuncker, C. gronovii Willd. ex Schult., C. umbrosa Beyr. ex Hook., C. epithymum (L.) L. and C. epilinum Weihe. Canadian Journal of Plant Science 86: 293-316.

Costea, M., Nesom, G. L. and Stefanović, S. 2006a. Taxonomy of the Cuscuta pentagona complex (Convolvulaceae) in North America. Sida 22: 151-175.

Costea, M., Nesom, G. L. and Stefanović, S. 2006b. Taxonomy of Cuscuta gronovii and Cuscuta umbrosa (Convolvulaceae). Sida 22: 197-207.

Costea, M., Nesom, G. L. and Stefanović, S. 2006c. Taxonomy of the Cuscuta indecora (Convolvulaceae) complex in North America. Sida 22: 209-225.

Costea, M., García, M. A. and Stefanović, S. 2015. A phylogenetically based infrageneric classification of the parasitic plant genus Cuscuta (dodders, Convolvulaceae). Systematic Botany 40: 269-285.

Costea, M., Spence, I., and Stefanović, S. 2011. Systematics of Cuscuta chinensis species complex (subgenus Grammica, Convolvulaceae): evidence for long-distance dispersal and one new species. Organisms, Diversity and Evolution 11: 373–386.

Costea, M., Wright, M.A.R, and Stefanović, S. 2009. Untangling the systematics of salt marsh dodders: Cuscuta pacifica , a new segregate species from Cuscuta salina (Convolvulaceae). Systematic Botany 34: 787–795.

Darbyshire, S. J. 2003. Inventory of Canadian Agricultural Weeds. Agriculture and Agri-Food Canada, Research Branch. Ottawa, ON.

eFloras. 2022. Electronic Floras. Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA., http://www.efloras.org Accessed July 15, 2022.

Global Biodiversity Information Facility (GBIF) Secretariat. 2022. https://doi.org/10.15468/39omei Accessed via https://www.gbif.org/species/2927479 Accessed December 29, 2022.

Government of Canada (GC). 2016. Canadian Weed Seeds Order. https://laws-lois.justice.gc.ca/eng/regulations/SOR-2016-93/page-2.html (English) https://laws-lois.justice.gc.ca/fra/reglements/DORS-2016-93/page-2.html (French)

Government of Canada (GC). 2019. D-12-01: Phytosanitary Requirements to Prevent the Introduction of Plants Regulated as Pests in Canada. https://inspection.canada.ca/plant-health/invasive-species/directives/date/d-12-01/eng/1380720513797/1380721302921 (English) https://inspection.canada.ca/protection-des-vegetaux/especes-envahissantes/directives/date/d-12-01/fra/1380720513797/1380721302921 (French)

International Seed Morphology Association (ISMA). 2020. Method for Seed Size Measurement. Version 1.0. ISMA Publication Guide.

Lanini, W.T. and Kogan, M. 2005. Biology and management of Cuscuta in crops. Ciencia E Investigacion Agraria 32: 127-141.

Lyshede, O.B. 1992. Studies of mature seeds of Cuscuta pedicellata and C. campestris by electron microscopy. Annals of Botany 69: 365-371.

Martin, A.C. 1946. The comparative internal morphology of seeds. The American Midland Naturalist 36: 513-660.

Olszewski, M, Dilliott, M, Garcı´a-Ruiz, I, Bendarvandi, B, and Costea, M. 2020. Cuscuta seeds: Diversity and evolution, value for systematics/identification and exploration of allometric relationships. PLoS ONE 15(6): e0234627. https://doi.org/10.1371/journal.pone.0234627

Press, M.C. and Phoenix, G.K. 2005. Impacts of parasitic plants on natural communities. New Phytologist 166: 737-751.

U.S. Department of Agriculture-Agricultural Research Services (USDA-ARS). 2022. Germplasm Resources Information Network (GRIN), https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysimple.aspx Accessed April 19, 2022.

U.S. Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS). 2022. The PLANTS Database. National Plant Data Team, Greensboro, NC USA. http://plants.usda.gov Accessed December 29, 2022.

Zhao, S. and Yang, J. 2017. Research Advances and Perspectives of the Chinese Traditional Medicine Dodder. Botanical Research 植物学研究, 6: 175-184.



Jennifer Neudorf, Angela Salzl, Ruojing Wang, Karen Castro, Katrina Entwistle
Canadian Food Inspection Agency