Read the following passage:
MOTHER NATURE
There are millions of herbivores—plant-eaters—on this planet, and their constant snacking can prevent young plants from reaching maturity and reproducing. So what’s a plant to do? Well, thanks to the wonders of natural selection, plants have evolved a number of defenses to prevent herbivores from eating them.
Many plants produce chemicals that have unpleasant effects. Some have poisonous or foul-tasting leaves, flowers, or fruit. Others, like poison ivy, poison oak, and poison sumac, can induce painful rashes on animals’ skin.
Thorns, which you can find on a variety of bushes, bite back when an animal chomps into them, as do leaves with barbs or spines. Saps and gums can be produced that trap herbivorous insects, and slippery, waxy leaves are very difficult for animals to eat. Other plants have leaves that physically close up in response to touch or vibrations.
There are also plants which enter into symbiotic relationships with other species. Trees in the genus Macaranga provide homes to ant colonies, which defend them from herbivores, while other plants have close relationships with fungi or microbes that are poisonous when eaten.
The weirdest defense mechanism we’ve heard of? When they’re attacked by herbivores, certain plant species release chemicals that attract carnivores—and when these predators show up, any herbivore that doesn’t run for the hills ends up as lunch.
Based on the passage, what can you infer that word "symbiotic" means?