Scientist observing tomato (Solanum lycopersicum) and parasitic dodder (Cuscuta sp., yellow) plants in bell jars as part of a study into sensing smell in plants. Dodder plants do not have roots or a means of carrying out photosynthesis. As such, the need to grow around other plants, such as tomato plants, in order to survive. Several studies indicate that the primary way dodders find tomato plants is by smelling volatile compounds they release, and growing towards them.