Allelopathy

Allelopathy is the secretion by plants of a toxic substance into the soil in order to prevent other plants from growing near them. This trait is most commonly exhibited in desert plants, where water is scarce and competition from other plants for it is a matter of survival.

Invasive plants

Centaurea maculosa Lam. (European spotted knapweed, Asteraceae) is an invasive plant in North America.

References

Ridenour, W.M., and Callaway, R.M. 2001. The relative importance of allelopathy in interference: the effects of an invasive weed on a native bunchgrass. Oecologia, 126: 444-450. doi: 10. 1007/s004420000533.