The appearance of Cuscuta pentagona is very different from that of ordinary plants. It is a slender orange-red vine that can grow to 3 feet[1] tall and bear tiny white flowers with five petals, which can be seen all over North America. What is unique about plants like dodder is that it has no leaves, and because it lacks chlorophyll—a pigment that absorbs the sun’s energy and is used by plants to convert light into sugars and oxygen during photosynthesis—its full None of the plants are green. Dodder apparently cannot photosynthesize like most plants, so it cannot use light to make its own food. Knowing this, we may think that dodder will starve to death, but the fact is the opposite, it is alive and well. Dodder feeds itself in another way—it gets its food from neighboring plants. It is a parasitic plant. In order to survive, dodder attaches itself to the host plant and grows an appendage deep into the vascular system of the host plant, thereby sucking the nutrients provided by the host. Because of this, it's no surprise that dodder, commonly known as "yellow silk," can harm agriculture and is classified as a "malignant weed" by the U.S. Department of Agriculture. What's really fascinating about dodder, though, is that it actually has a taste preference—it picks out specialized species to attack among neighboring plants.
Before exploring why dodder has a very discerning taste preference, let's take a look at how its parasitic life began. Dodder seeds will germinate like the seeds of other plants. Seeds buried in the soil crack, new shoots emerge from the ground, and new roots burrow into the soil. However, dodder seedlings that grow alone will die if a host plant is not found quickly. As a dodder seedling grows, its shoot tips make small circular motions to probe the surroundings, just as we keep groping with our hands when blindfolded or searching for a kitchen light in the middle of the night. Such a movement may seem aimless at first, but if the dodder is next to another plant—a tomato, say—it will quickly bend and grow noticeably in the direction of the tomato that feeds it. , spin, and so on, until you find the tomato leaves. However, the dodder does not touch the leaves of the tomato, but continues to move downward until it finds the stem of the tomato. In the latter triumph, the dodder wraps around the tomato stem, piercing the tiny protrusions into the tomato's phloem (the conduit for the sugary juice), and begins sucking up the sugar so it can continue to grow and eventually bloom. Oh, while the dodder was thriving, the tomatoes began to wilt.
Dr. Consuero de Morais simply made a video of the act. [2] She is an entomologist at Penn State University with a primary research interest in understanding volatile chemical signaling between insects and plants. She has a research program whose main purpose is to figure out how dodder locates its prey. She found that dodder vines never grow into empty pots or pots with fake plants, and they never turn back toward tomatoes—whether she puts them in the light or the shade. Demoraes deduced that the dodder was actually sniffing the tomato. To test the hypothesis, she and her students placed dodders in pots in one airtight box and tomatoes in another. The two boxes are connected by a pipe, and one end of the pipe leads to the box where the dodder is located, which allows air to flow freely between the two boxes. The isolated dodder always grew towards the pipe, suggesting that the tomato released an odor that wafted through the pipe to the box where the dodder was in, and the dodder loved it.