How do the plants of the biome contribute to the biome?

The mediterranean is the same as chapparal

The dominant plants of the desert biomes would depend on what desert you are referring to. In the Mojave, for instance, the more dominant plants would be cacti, mesquite trees and Joshua trees. In...

its underneath a plant leaf. under rocks and ledges.

mostly tropical plants such as fly traps palm trees etc.

The tropical rainforest does. Some include bamboo, cocnut tree, grass, many bushes.