Calamansi is the Philippine English spelling of Tagalog kalamansi ), and is the name by which it is most widely known in the Philippines. In parts of the United States, notably Florida, calamansi is also known as “calamondin”, an old name from the American period of the Philippines. It is an anglicized form of the alternate Tagalog name kalamunding.
Other English common names of calamansi include: lemonsito (or limoncito), Philippine lime, calamondin, calamondin orange, calamandarin, golden lime, Philippine lemon, Panama orange (also used for kumquats), musk orange, bitter-sweets and acid orange.
Fruit of variegated calamansi
Calamansi was formerly identified as Citrus mitis Blanco, C. microcarpa Bunge or C. madurensis Lour. All those referred to it as a citrus. Swingle’s system of citrus classification put kumquats into a separate genus, Fortunella, making the calamansi an intergeneric hybrid. In 1975 it was given the hybrid name × Citrofortunella mitis by John Ingram and Harold E. Moore based on Blanco’s species name, D. Onno Wijnands pointed out that Bunge’s species name, C. microcarpa predated Blanco’s Citrus mitis making Citrofortunella microcarpa the proper name. Phylogenetic analysis now places the kumquat within the same genus as other citrus, meaning that its hybrids, including those formerly named as Citrofortunella, likewise belong in Citrus