When Portuguese explorers arrived there in the early 1400s, they were so impressed with the thick forest covering the steep, mountainous island that they called it Ilhe de Madeira, Island of Wood. The forest of Madeira is known as Laurissilva, a forest that is similar to high-altitude tropical rain forests ("cloud forests").
Laurissilva is a relic of the forest that once thrived across southern Europe and North Africa, but which disappeared as the last ice age ended and the regional climate became hotter and drier. Madeiras mild, subtropical climate and isolation preserved the laurel forest as it became extinct elsewhere.
The surviving Laurissilva is both a natural reserve and a World Heritage Site. The remaining forest covers about 15,000 ha, making it the largest Laurissilva forest in the world. About 90% of the forest is believed to be old growth, primary forest, according to the UN. The Laurissilva includes a wide diversity of flora, including a number of rare ferns and flowering plants.