Metroxylon sagu, commonly known as the sago palm, is a species of large, clustering tropical palm native to the lowland freshwater swamps, peat swamps, and riverine floodwaters of Southeast Asia, particularly Indonesia (especially New Guinea and Maluku), Malaysia, and the Philippines. Belonging to the family Arecaceae, the genus name Metroxylon is derived from Greek roots meaning "heart-wood," while the species epithet sagu comes from the Malay word sago or sagu', referring to the starchy food extracted from the trunk. The sago palm is one of the world's most ecologically unique and culturally significant starch-producing plants, serving as a vital traditional staple carbohydrate for indigenous populations across the Malay Archipelago long before the widespread cultivation of rice.

The plant is a massive, monocarpic palm, meaning each individual stem flowers and fruits only once before dying off, though the plant as a whole survives through continuous basal suckers (offshoots) that form a dense clump. The robust, single trunks can grow up to 10 to 20 meters tall and nearly a meter in diameter, marked by distinct ringed leaf scars and protected in some varieties by sharp, defensive spines. The crown bears enormous, elegant pinnate leaves (fronds) spanning several meters in length. After maturing over a span of 7 to 15 years—just prior to flowering—the trunk accumulates an immense reserve of starchy pith to fuel its massive reproductive effort. It is at this peak vegetative stage that the palm is traditionally harvested for sago extraction.

In culinary applications, the sago palm is globally renowned as the primary source of authentic sago starch. The harvesting process involves felling the mature trunk, splitting open its woody outer bark, and rasping the fibrous inner pith into a soft pulp. This pulp is thoroughly washed and kneaded with water to filter out the pure starch granules, which settle in water tanks and are subsequently dried into crude flour, pearl sago, or flakes. In traditional regional cuisines—particularly in parts of Indonesia, Malaysia, and Papua New Guinea—sago starch is boiled into a thick, sticky, translucent paste (known as papeda or ambuyat) that is eaten with savory fish soups and vegetable stews. Globally, pearl sago is widely utilized in desserts, traditional puddings, baking, and chewy bubble tea beverages, though commercial pearls are frequently substituted with cheaper tapioca starch.

Nutritionally and industrially, sago is a pure carbohydrate source consisting almost entirely of easily digestible amylose and amylopectin starches, providing a high-calorie dietary staple for tropical lowland regions where cereal crops struggle to grow. Because it is naturally gluten-free and hypoallergenic, sago starch is valued in modern food processing as a thickening agent for soups, sauces, and confections. In traditional medicine, various parts of the plant have been used locally; warm poultices made from the pulp or bark were occasionally applied to soothe insect stings and minor skin inflammations.