Thought to be a strain of Tangelo, a cross between a grapefruit and a tangerine, the fruit is amazingly sweet and juicy with a thick rind that peels easily. The plant grows slower than most lemon trees yet when it reaches two or more feet it will flower and fruit with great regularity.Tiny, bright orange kumquats hang like ornaments on the kumquat tree, making it a beautiful and fragrant houseplant. These are easy to grow and easy to maintain. The fruit closely resembles the orange in color and shape but is much smaller. It is a good source of vitamin C and also helps to boost your immune system.