西米是由几种棕榈树树干内所储碳水化合物制做的食用淀粉。原料是西米棕榈，主要为原产于印度尼西亚群岛的metroxylon rumphii和西谷椰子，还有桄榔、酒假桄榔caryota urens。南美洲生产西米的原料则来自mauritia flexuosa和guilielma gasipaes。

西米棕榈生长在低洼沼泽地，通常高9米，干粗。15年成熟后长出一花穗，茎髓充满淀粉。当果实形成和成熟时，便吸收淀粉，是茎干中空。树在果熟后死去。

栽培的西米棕榈在花穗出现时砍断花穗，从树干中取出含淀粉的髓磨成粉，加水在滤器上方揉捏滤去木质纤维，洗涤数次后得西米粉，在当地食用。外运的西米是加水调成糊状，然后搓磨通过筛子，制成颗粒，根据颗粒大小分为珍珠西米或弹丸西米。

Sago /ˈseɪɡoʊ/ is a starch extracted from the spongy centre, or pith, of various tropical palm stems, especially Metroxylon sagu. It is a major staple food for the lowland peoples of New Guinea and the Moluccas, where it is called saksak, rabia and sagu. A type of flour, called sago flour, is made from sago. The largest supply of sago comes from the East Indies. Large quantities of sago are sent to Europe and North America for cooking purposes. It is traditionally cooked and eaten in various forms, such as rolled into balls, mixed with boiling water to form a paste, or as a pancake. Sago is often produced commercially in the form of "pearls". Sago pearls can be boiled with water or milk and sugar to make a sweet sago pudding. Sago pearls are similar in appearance to tapioca pearls and the two may be used interchangeably in some dishes.