This genus comprises approximately 170 species of parasitic plants, known in English as dodder — a word of of Germanic origin; related to Middle Dutch, Middle Low German dodder, Middle High German toter. They are nearly chlorophyll-less plants, devoid of leaves, yellow, orange or red in color. They exist as vines that attach themselves to a variety of other plants. The tiny dodder seedlings are unable to survive more than a few days after germination without finding a host plant.
Dodder grows a link to its host, so as to steal water and nourishment from it. These suckers are termed haustoria, from a Latin verb, haurire, meaning ‟to haul from‟. Fungi are other organisms that grow and depend likewise on predatory haustoria. The dodder haustoria insert themselves into the vascular system of the host.
Once connected to a host, a dodder vine not only weakens it by usurping its metabolism, using the duct to inject a variety of chemicals, including viruses that will turn a healthy plant into a diseased one. Hence, dodders are an agricultural pest. Some of the crops thus attacked are olive trees, acacias, carrots, potatoes, beet, eggplants, tomatoes, thyme, clover, alfalfa, soybean and tobacco.
Vineyards can also become victims. Our vocabulary reflects the hostility that has grown over the centuries about dodder: wizard’s net, witches’ hair or devil’s gut are some of the nicknames.
Mycorrhyzae, already described in this series, are symbionts rather than parasites. They form an underground resistance network. In a similar manner, but above ground, dodder provides a network by which plants can resist aggression. By embracing other plants the dodder vines build connections for chemical communication within that particular ecosystem. Multiple adjacent hosts are often parasitized by one or more Cuscuta plants simultaneously, forming connected plant clusters. When a parasited plant is attacked by an herbivore insect, it signals its distress with release of jasmonic acid. Unattacked plants, thus warned via the dodder haustoria, switch on their chemical defenses against the insect. This defense mechanism works over significant distances, of at least a meter. How does it work? By boosting production by the threatened plant of trypsin proteinase inhibitors, chemical weapons against insect digestive enzymes. Thus, the dodder repays — a little — the hospitality it enjoys.