New Caledonia is known for the diversity of its geological substrates, which have shaped its highly original and diverse flora. Here, the effect of the soil on the vegetation is described for several contact zones between ultramafic and other substrates. The main vegetation formations on soils derived from ultramafic rocks are described: low and medium altitude rainforests, high altitude rainforests, and maquis. The main types of maquis and the biological characteristics of maquis species are also presented.