Long Yan Rou
Botanical name: Dimocarpus longan
Common name: Longan fruit
Literal name translation: dragon eye flesh
Family: Sapindaceae, soapberry family
Part used in Chinese medicine: flesh of fruit
Major Chinese medicine actions:
Nourishes blood, tonifies qi, calms spirit, tonifies Heart and Spleen
Photo Credits: (top to bottom)
Photo 1: Dimocarpus longan; 03/2006; author Scott Bauer, USDA; permission under GFDL
Photo 2: Dimocarpus longan; 08/2004; author Elijah van der Giessen; permission under GFDL
Photo 3: Dimocarpus longan; 2007; author Minha Autoria; permission under GFDL
Longan is native to southeast Asia and is a close relative of the lychee. It has been grown for thousands of years and is now cultivated throughout the tropic and subtropics, grown in the U.S. in Florida and Hawaii. It is a large, long-lived evergreen, considered a subtropical tree. It does best in temperatures that stay above freezing, but is known to survive down to 26 degrees F, though with some damage.
The tree grows to 50 feet high, with small yellow-green flowers blooming from November to April. In order for the tree to produce flowers and bear fruit, it must have a “rest” period. Though not a true dormancy, cool temperatures are necessary for inducing flower development. Longan fruits are round with a light brown peel, a shiny black seed in the middle, and translucent white flesh that is very sweet. It is sometimes called “dragon’s eye fruit” because the fruit resembles an eyeball and when shelled, and the black seed shows through the translucent flesh like a pupil.
Growing and Propagation
The longan does best in environments with warm, humid summers and cool, dry winters. It is adaptable to a wide variety of soils but does not tolerate water-logging. It thrives best in fertile, rich soil with a pH of 5.5 – 6.0. Fertilization is helpful for promoting tree growth, but should be discontinued from September to March to encourage flowering. Young trees should be fertilized every 4 months in the first two years of growth with a 14-14-14 fertilizer, then for mature trees, fertilized every 3 months.
Longan can be propagated by seed, cuttings, air layers or grafting. Seeds lose their viability quickly and should be kept moist or planted within 4-5 days of removal. Air layering is the most common method of propagation but results in trees with weak root systems that can be blown over in strong winds. Trees grown from seed are stronger but take 7 or more years to bear fruit, while grafted or air layered trees produce in 3-4 years or less.
Harvesting and Preparation
Fruit yields vary due to flowering and fruit set variations from year to year. Mature trees can produce up to 500 pounds of fruit per year while in some years there may be no fruit formed at all. Fruit is harvested in mid May to July when the entire panicle, or group of fruits on a single stem, is cut and dried. For medicinal use, good quality Long Yan Rou is large and soft with a yellowish translucent color and sweet taste.