Calamondin. Citrus mitis a.k.a. Panama orange, Scarlet lime, Golden lime. Small citrus fruit resembling a miniature tangerine. Fruits are very juicy, with a sweet but acidic flavor. Common in tropical zones, but lesser known elsewhere.
Easy to grow. Bears 2" orange fruits which are sour - like lemon. Aside from being an attractive ornamental tree its fruits make excellent preserves and the juice is a great lemon substitute. Mature height is 6' and it may be pruned. A willing indoor grower with bright light. The tree is a heavy producer of fruit and its masses of small white blossoms are intensely fragrant and flowering much of the year.
Leaves are smaller than most citrus. The calamondin is hardy to temperatures in the mid 20's. It can be successfully grown outside throughout California, Florida, and the gulf coast. It makes an excellent house plant or patio plant in colder areas. Propagation: Often by seed, (unlike many other citrus). Seeds are polyembryonic and may produce up to 3-5 seedlings each. Eaten raw, although the flavor is very acidic. Often used to flavor drinks, jellies, and a variety of foods. Native to China. Has now spread throughout much of the South Pacific and the Americas.