Skip to content
Elisabeth C. Miller Library

Keyword: Cuscuta

on dodders

While hiking on San Juan Island, I saw these strangely beautiful, fluorescent orange clumps of hair-like substance (plant? fungus? something from outer space??) interwoven through the succulent-looking marsh plants. Can you tell me what this is?

 

That weaving (or strangling!) habit you describe calls dodder to mind, and there is a native coastal salt marsh dodder in that area called Cuscuta pacifica. Dodder is related to morning glories (the plant family Convolvulaceae). It is a rootless parasitic plant with nearly no chlorophyll and barely any leaves, and cannot photosynthesize on its own. It sustains itself by twining around other flowering plants and infiltrating their tissues with specialized branches on its stems, and coiling around them repeatedly as it grows. It may even be able to “smell” potential host plants.

Dodder can weaken its host plants, rendering them vulnerable to disease. However, there is some evidence that by thinning out the dominant host plants in a given area, it makes room for other species to take hold, increasing diversity.

The Washington State Noxious Weed Control Board lists a non-native species (Cuscuta approximata, smoothseed alfalfa dodder) as a Class C noxious weed, but it is not found in the area where you were. It is mainly a problem in agricultural land east of the Cascades. Dodder has various unfriendly nicknames in farming land: Devil’s Guts, Witches’ Shoelaces, Strangleweed, to list a few.

on the parasitic plant dodder

I’m doing a science fair project on dodder plant and I’m seeking information about the plant, and a source of seeds or plants for the project.

 

Dodder is a parasitic plant that lives on crops, ornamentals, native plants, and weeds. Because it has limited chlorophyll, it can’t make enough food to support
itself, and so relies on the plants it colonizes for nourishment. It belongs to the genus Cuscuta, in the family Convolvulaceae (same family as morning glory). It was formerly referred to as Grammica.

Perhaps the reason that seeds and plants are not readily available is that dodder causes great damage to the plants it parasitizes. The U.S. Department of Agriculture’s plant protection and quarantine office states that “products, including foods, containing whole dodder seeds (Cuscuta spp.) are prohibited entry into the United States. APHIS regulates whole dodder seeds, both as a parasitic plant pest under Title 7 Code of Federal Regulations (CFR), Part 330 and as a Federal noxious weed under Title 7 CFR, Part 360.”

Here is additional information from University of California, Davis’s Integrated Pest Management website. Dodder is sometimes referred to as the “Vampire Plant,” as this University of Florida Extension page explains. Although your project, safe within the confines of a lab or classroom, might pose no threat, it is not legal to sell Cuscuta seeds or plants in the U.S.