Kumquat

Kumquat plants have thornless branches and extremely glossy leaves. They bear dainty white flowers that occur in clusters or individually inside the leaf axils. The plants can reach a height from 2.5 to 4.5 meters (8 to 15 feet), with dense branches, sometimes bearing small thorns. They bear yellowish-orange fruits that are oval or round in shape. The fruits can be 2.5–5 centimeters (1–2 inches) in diameter and have a sweet, pulpy skin and slightly acidic inner pulp. The fruit is often eaten whole by humans and has a taste that is sweet and somewhat sour. Kumquat trees are self-pollinating.

The kumquat plant is native to Southern China. The first historical reference to kumquats appears in literature of China from at least the 12th century. They have been cultivated for centuries in other parts of East Asia, South Asia, and Southeast Asia. They were introduced into Europe in 1846 by Robert Fortune, collector for the London Horticultural Society, and have spread across the world.

A raw kumquat is 81% water, 16% carbohydrates, 2% protein, and 1% fat (table). In a reference amount of 100 grams (3+1⁄2 ounces), raw kumquat supplies 296 kilojoules (71 kilocalories) of food energy and is a rich source of vitamin C (49% of the Daily Value), with no other micronutrients in significant content (table).

Kumquats are much hardier than citrus plants such as oranges. Sowing seeds in the spring is ideal because the temperature is pleasant, with more chances of rain and sunshine. This also gives the tree enough time to become well established before winter. Early spring is the best time to transplant a sapling. They do best in direct sunlight (needing 6–7 hours a day) and are planted directly in the ground. Kumquats do well in USDA hardy zones 9 and 10 and can survive in temperatures as low as 18 degrees Fahrenheit (−8 degrees Celsius). On trees mature enough, kumquats will form in about 90 days. In cultivation in the UK, Citrus japonica has gained the Royal Horticultural Society's Award of Garden Merit (confirmed 2017).

Propagation. Kumquats do not grow well from seeds and so are vegetatively propagated by using rootstock of another citrus fruit, air layering, or cuttings.

Varieties. The Nordmann seedless is a seedless cultivar of the Nagami kumquat (Citrus margarita). It is similar to Nagami but with a slightly different shape and lighter skin. The Centennial Variegated is another cultivar of the Nagami kumquat. It originated from the open pollination of a Nagami kumquat tree. The fruits are striped light green and yellow when underripe, and turn orange and lose their stripes when they ripen. They are oval-shaped, necked, 2.5 inches long, and have a smooth rind. …

The English word kumquat is a borrowing of the Cantonese gām gwāt (IPA: [kɐ́m kʷɐ́t̚]; Chinese: 金橘), from gām 'golden' + gwāt 'mandarin orange'.