Many people notice the stringy, orange vines that grow over many of San Diego’s shrubs. It tends to show up more in spring and summer than in the winter. It definitely stands out, especially when its orange vines lies across bright green plants. It’s mostly known by its common name: witches’ hair. It’s also known by its proper name, dodder and sometimes known as witch’s broom.
Dodder is a common, naturally occurring parasitic plant in California. There are eight species of it in the state. There are species suited for freshwater and salt water/brackish areas. It’s part of the morning glory family and actually produces flowers in late summer, but no leaves. It’s not poisonous to handle unless it’s feeding off a poisonous plant. Some animals, such as deer, will eat certain types of dodder.
When dodders erupt from their seed, they have to find a host plant within a few days or it dies. Studies have shown that it finds a host by sensing certain chemicals. They have a preference for softer plants like tomatoes, but will grow on any plant where it can break through their stems. Here in San Diego, they tend to feed off of shrubbery, including coastal sage scrub and softer varieties of cactus. It also feeds off a variety of agricultural crops and ornamental plants.
Dodder attaches itself to a plant and drains its nutrients and water, sometimes causing part of the plant to die or produce less fruit. After it flowers, it begins to grow small fruit which contains its seed. Being an annual plant, it will most likely die after fruiting. However, if the seeds land close to the host plant, new dodders will grow to feed off the same plant the next year.
Dodder is considered to be a severe agricultural pest and active measures are being taken to prevent its spread. Some of these steps include close inspection of imported plants and quarantines. People also unknowingly spread dodder when they step through infested areas or move dirt around, so awareness is crucial. If you encounter this plant, be careful to rinse or remove any clothing or body part that touched the plant before handing other, healthy plants.