Dodder is a vine with no roots and hardly any ability to feed itself, so a seedling has only what was packed in the seed, and it must find something to live on before that runs out. In 2006 researchers showed how it looks: it smells. Seedlings grew toward a tomato plant, and toward tomato scent with no plant there at all. Pots of damp soil, an artificial plant and vials of coloured water got nothing. Then they were offered tomato or wheat, and they leaned toward the tomato. It has almost nothing in the world and it is still a picky eater.