Parasitic Plants

Plants make their own food, right? At least that’s what most of us have been told all our lives. Plants get the energy needed to survive from sugars that they make themselves through photosynthesis. A crucial element of this process is light, which provides the energy needed to synthesize sugars. Photosynthesizing plants are characteristically green, due to a pigment called chlorophyll. However, some plants grow and thrive without ever needing chlorophyll or light. These plants, commonly known as parasitic plants, feed off of other plants that they are attached to.

Image of the Cuscuta spp. vine latching onto a flower (link here)

Parasitic plants are usually more difficult to spot than photosynthesizing plants. Their color varies widely, from purple to yellow to bright red. Without the need for light, some species grow mainly underground. Others completely cover the victim plant, cutting off the victim’s sunlight and making it more vulnerable to the parasitic plant.

The dodder vine, a stem parasite, covers the plant it is attacking and suckers onto it, draining the plant before moving onto the next host. The vine does this with a haustorium, a unique organ that creates a vascular link between the two plants. The haustorium is a highly modified root or stem of the parasite.

A yellow dodder vine taking over a desert bush (image link here)

The dodder vine seen above is cutting off the host plant's light. Using the haustoriums, the dodder vine will take nutrients and water from the plant until the vine dies. The seeds left by the parasitic vine will then make use of new host plants.

These plants can be harmful to crops and agricultural farms. Different types of parasitic plants destroy cereal crops, legumes, corn, and many other broadleaf crops.

Stalk of a Cistanche tubulosa (desert hyacinth) popping up (image credit here)

These plants have an amazing advantage in their ecosystems. They do not need to produce their own food through photosynthesis, which takes a lot of time and energy, as they leech what they need from other plants. Other plants that are doing the work of photosynthesis are losing their hard work to these parasites. They have evolved to do as little work as possible, and that works for them.

Parasites are difficult to get rid of because many of them are underground, but researchers are developing new ways of fighting them, such as interfering with the ability of the parasites to bind to a host. These vampire-like plants pose an interesting challenge to the field of agricultural research.