The greatest diversity in plant species can be found in ______.

Rain forests belong to the tropical wet climate group. Rainforests now cover less than 6% of Earth's land surface. Scientists estimate that more than half of all the world's plant and animal species, live in tropical rain forests. Tropical rainforests produce 40% of Earth's oxygen. A tropical rain forest has more kinds of trees, than any other area in the world. Scientists have counted about 100 to 300 species, in one 2 1/2-acre (1-hectare) area in South America. Seventy percent of the plants in the rainforest, are trees.