Unlike most other citrus, Kumquats are small and olive-shaped with a thin, delicate peel that may be consumed with the rest of the fruit. Originally native to China, Kumquats proliferate on dark green, leafy trees that when mature can bear hundreds of fruits. Their peel is sweeter than their flesh, and should be smooth, shiny and bright orange. Kumquats are excellent for marmalades and jams, sliced thin and used in marinades, or sautéed with leafy greens for a punch of flavor.