With 40,000 species of flowering plants, including 3,000 trees and 5,000 orchids, Indonesia has a greater variety of flora than the tropical regions of Africa or the Americas. Indonesia is home to the very large and smelly corpse lily (see Rafflesia). Orchids are also abundant, and Indonesia is home to the largest of all orchids, the tiger orchid. The insect-trapping pitcher plant is found throughout western Indonesia.

Tropical rain forests prevail in the northern lowlands of Indonesia. Tall tropical hardwoods dominate the forests and provide good harvests of timber, resin, vegetable oil, and illipe nuts. Mangrove trees and nipa palm dominate the forests of the southern lowlands. The hill forests consist of oak and chestnut trees and mountain plants.

The animals of Indonesia are separated by Wallace’s Line (see Natural Regions above) into the Indo-Malayan and Austro-Malayan zoogeographic regions. The Indo-Malayan region includes Java, Kalimantan, and Sumatra and has species linked to mainland Asia. Orangutans live in the forests of Sumatra and Kalimantan. Wild oxen, also known as banteng, are in Kalimantan and parts of Java such as the Ujung Kulon National Park in western Java. Proboscis monkeys (bekanten) can be found in Kalimantan, and elephants, tapir, and siamangs (black gibbons) inhabit Sumatra.

In the late 1990s about 400 Sumatran tigers, an endangered species, remained in Sumatra. Even in the national parks it is estimated that at least 14 are killed each year, some by poachers, others by villagers because the tigers prey on pigs. The tigers of Java (commonly, the Javan tiger) are believed to be extinct, and on Bali they are long extinct.

The animals of the Austro-Malayan region are linked to Australia. Papua is home to the large, flightless cassowary bird and to many species of colorful birds of paradise.

Maluku, Sulawesi, and the Lesser Sunda Islands lie between the two larger regions and have somewhat distinctive animals drawn from both. Maleo birds are native to Sulawesi. The phalanger, an Australian type of marsupial, is found on Timor. The Komodo dragon, of Komodo and Rinca islands, is the world’s largest lizard, growing to 3 m (10 ft) in length.