They probably arose through allopatric speciation, with citrons evolving in northern Indochina, pummelos in the Malay Archipelago, and mandarines in Vietnam, southern China, and Japan.
12.
Both are cross-breeds of everyday white grapefruit with pummelo _ the large, thick-skinned grapefruit that has grown for centuries in China and is the mother of all citrus plants.
13.
Right now, they are available only in stores like Central Market or Whole Foods, but if they catch on, you might soon be able to swing by the Stop'n Go for a fresh pummelo.
14.
Many fruit sold as mandarins are in fact hybrids with some pummelo ( " C . maxima " ) ancestry, and are thus on a continumn with clementines, sweet and sour oranges, and grapefruit.
15.
Notable species in the Citrinae group include Bergamot orange, calamondin, citron, grapefruit, lemon, orange, pummelo, tangelo, and tangerine, all of which are in the genus " Citrus ".
16.
It shows 370 varieties, obviously too many to fit in the chart, but for instance limetta ( # 58 ) is represented clearly as a pummelo ( ~ 1 / 5 ) x citron ( ~ 4 / 5 ), so my " mandarin " guess was wrong.
