It has been a long time since I saw any dodder (Cuscuta sp.). A few days ago when Leonard and I were leaving the McArthur Swamp (Shasta County CA) I noticed patches of distinctive orange spreading across the foliage on the ground. Dodder! We HAD to go back so I could check it out.
There are many species of dodder, all of which are parasitic on varying hosts. The plants have no chlorophyll and depend on their hosts for survival. The characteristics for distinguishing the various dodders are so technical that for us amateurs it is difficult to determine the species. However, longseed dodder (Cuscuta indecora) and field dodder (Cuscuta campestris) are our common local species, so very likely this dodder is one of the two.
Dodder species are native annuals that can be found throughout all of the United States. A twisting vine that is related to the morning glory, dodder forms a mat of wiry orange stems over the host plant. The leaves are reduced to minute scales. Small, fleshy, creamy white, five-lobed clusters of flowers form along the stems in late summer. (Unfortunately I could find no flowers on these plants, but will check again later in the season.) The globe-shaped seed pods are covered by withered petals and contain two to four seeds each.
Dodder seeds are long-lived in the soil and are produced in large quantities, thus providing a survival mechanism until host plants are available. The seeds also contain a minute quantity of chlorophyll and can weakly photosynthesize immediately after germination. The seedling is a long, slender threadlike stem that rotates slowly and twines around until, using chemosensory cues, it finds a host plant. If after five to ten days a host plant is not located, the embryonic food reserves and photosynthesizing abilities can no longer support the seedling and it dies. If the dodder seedling finds a host it penetrates the plant with wart-like suckers (called haustoria). The lower part of the dodder plant withers and it permanently loses connection with the soil and is totally parasitic. Once attached to the host, a dodder plant will begin to branch and send “tentacle” stems toward other nearby plants and parasitize them too. When the host plant dies, the portion of the dodder attached to the dead plant also dies, but the remainder of the dodder plant, by now attached to other host plants, lives.
In addition to being classified as wildflowers, Cuscuta species are considered noxious weeds because they kill and can overrun cultivated fields and crops, particularly clover and alfalfa, as well as other herbaceous plants, shrubs and even trees.
Other common names for dodder are lovevine, devil’s hair, hairweed and strangleweed.
I think dodder is a fascinating plant, one that could easily star in an “aliens from outer space” movie.