Figure 1. Many Species Commonly Grown throughout the World Can Become Invasive When Introduced to New Ecosystems.

(A) The California poppy (Eschscholzia californica) has invaded many parts of the world (e.g., Chile, Turkey, and New Zealand), and is commonly grown in many European and American gardens.

(B) The blue gum tree (Eucalypus globulus)—featured here in a plantation in Spain—is one of two of the most commonly planted trees in the world, the other being the Monterey Pine.

(Photos: Dov Sax)