Calamoideae is a subfamily of flowering plant in the palm family found throughout Central America, South America, Africa, India, China, Southeast Asia and Australia. It is represented by 21 genera - containing nearly a quarter of all species in the palm family - including the largest genus, Calamus, the type genus of the group. Only four are found in the New World while the rest are Old World denizens, usually found in equatorial swampland or along tropical coastlines.

While the many species show marked differences, the bracts of all orders are tubular, the flowers are almost always borne in dyads or dyad derivatives, but most marked as an identifier among these palms are the overlapping scales covering the fruit; occasionally small and irregular they are, in most cases, neatly aligned in vertical rows. Also common to the group are varying forms of armament: spines along leaf margins or on sheaths, root and stem spines, reflexed rachis cirri, or specialized hooks among the climbing species.

The long fossil record and the many unspecialized features imply the group diverged early, parallel perhaps, with the Coryphoideae from an ancient protopalm ancestor. While the simplest floral characteristics belong to those rattan genera endemic to Africa (Laccosperma, Eremospatha and Oncocalamus), they exhibit tremendous diversity suggesting a larger representation in the past. This subfamily has been noted in palm literature as the Lepidocaryoideae, however an 1844 (Griffith) designation of Calamoideae predates the use of the former at this rank and, as such, is correct in botanical nomenclature.

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