Among the chief productions of the plains are rice (the staple export of the country); pepper (chiefly from Chantabun); sirih, sago, sugar-cane, coco-nut and betel, Palmyra or sugar and attap palms; many forms of banana and other fruit, such as durian, orange-pommelo, guava, bread-fruit, mango, jack fruit, pine-apple, custard-apple and mangosteen.
The Ombilin, issuing out of the lake on the east side and flowing through a plateau of Eocene sandstone, has on its banks the coalfields of Sungei Durian, &c., but is not serviceable as a waterway for that part of Sumatra.
The Pteropus edulis (kalong, flying fox) is to be met with almost everywhere, especially in the durian trees.
Jack-fruit or durian, the tough spiny hide of which is torn open with their strong fingers, forms the chief food of orang-utans, which also consume the luscious mangustin and other fruits.
Gutta-percha (getah percha in the vernacular), camphor, cinnamon, cloves, nutmegs, gambir and betel, or areca-nuts, are all produced in the island; most of the tropical fruits flourish, including the much-admired but, to the uninitiated, most evil-smelling durian, a large fruit with an exceedingly strong outer covering composed of stout pyramidal spikes, which grows upon the branches of a tall tree and occasionally in falling inflicts considerable injuries upon passers-by.