A parasitic vine sniffs out which plant to strangle before it ever touches one
Dodder (Cuscuta) has almost no roots, leaves or chlorophyll of its own, so its seedlings sweep their stem tip in slow circles, growing toward whichever nearby plant releases the strongest airborne chemical cues. In lab tests, seedlings reliably chose a nutrient-rich tomato plant over a poorer wheat seedling by scent alone, with no light or touch involved. Once it reaches a host, it pierces the stem with root-like haustoria and drains its water and nutrients.