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Longan

Longan


Family: Sapindaceae
Genus: Dimocarpus
Species: longan (alternate Nephelium longana)

The longan or dragon's eye is the more temperate relative of the glamorous lychee. Many Chinese prefer the longan to the lychee since it has a distinctive musky flavor and is not overly sweet. The tree is better adapted to California than the lychee, particularly since it is more frost tolerant (22oF). The round fruit is smaller than the lychee. The outer shell is relatively smooth and dark tan in color. The aril surrounds a single (usually) large brown seed. The fruits are available fresh, frozen, canned and dried. Longans have less finicky fruiting habits than lychee. Propagation is costly since marcottage must be used. A market demand exists in the Asian community for the fresh fruit which is available only in limited quantities, if at all.

Botany

The soapberry family, Sapindaceae, includes several thousand tropical and temperate species. The two most commonly eaten species in the Americas are the akee (Blighia sapida) and the Spanish lime (Melicocca bijuga). The akee is the national fruit of Jamaica even though it is poisonous when underripe or overripe. Although Spanish lime or genip is found from Columbia to southern Florida, it has received little horticultural attention because of the size and acidity of the fruit. Both are considered too tender to grow in California.

The longan tree grows 15 to 25 feet in California versus 50 feet under ideal conditions. The tree is heavily foliated and about as wide as it is tall. Its leaves are alternately pinnate, with 4 to 10 opposite, lanceolate, 6 to 8 inch leaflets that are noticeably larger than those of the lychee. The floral clusters of intermixed, creamy white male and female flowers which are larger than the lychee, are followed by round .5 to 1 inch, smooth, brown shelled fruits. In California fruit is borne over a 3 to 4 week period sometime from late July to December depending primarily on the location in which the tree is planted. Although, fruiting is less capricious than the lychee, many of the same techniques are employed to induce fruiting including girdling, withholding fertilization until after fruit sets, withholding water, and other practices that will produce sufficient stress to induce fruiting. The grape-like aril is semisweet with musky overtones that are not present in the lychee and its cousins, the rambutan and pulasan. Once the taste is appreciated the fruit is often preferred to the lychee. Trees started from marcots will bear in 3 to 5 years.

Climatic requirements

The longan is less fussy climate-wise than the lychee. Even so, young trees should be protected from cold and hot, dry winds. Hardened-off mature trees can withstand temperatures as low as 22o F for short periods of time.

Soil Requirements

The longan is adaptable to many different soil conditions, but it does best on rich soils that are well drained and on the acid side.

Cultural Requirements

Since longans have been planted on a very limited scale and no large plantings have been made in California, specific cultural recommendations must all be termed 'tentative'.

Spacing and training

Since the trees are somewhat smaller than the lychee, closer tree centers would be appropriate (15 to 25 feet).

Watering

The longan needs less water than the lychee. In California water requirements should be about equal to those of the lemon.

Fertilization

Data on fertilizer requirements are limited. In New Zealand balanced fertilizers are used; in China night soil is applied after flowering (in California manure could be used).

Pruning

Pruning requirements are minimal and should be limited to removing dead growth and shaping as desired.

Pests and Diseases

In California the tree should be pest free. In general, most sources agree that the longan is freer from pests than the lychee.

Propagation

Seedlings are considered too variable to be reliable producers. Clonal reproduction is normally done by marcotting since cuttings, even under well controlled conditions, are fairly difficult to root. Grafting is also not considered reliable enough for common commercial practice; however, inarching is used in China.

Harvesting and Storage

Fruit is harvested in clusters. Individual fruits can clipped off later and packed in polyethylene bags as are lychees. Partially ripe fruits can not be ripened after picking. No data exist for storing longans, however, they should store at least as well as lychees at 30o to 45oF for up to 3 months.

Fiscal

(To be determined)

Market

Fresh longans are seldom if ever available in California. However, a market demand likely exists since canned and frozen longans are popular in Californian Asian communities. In other communities, longans could be a difficult market to establish since they often require an acquired taste, especially when compared to lychees. However, if a lychee market is established, longans may be accepted as an extension of the lychee fresh fruit season since longans bear later.


Cultivars

Some varieties originating in southeast Asia are now becoming available in California. These have not been as well documented and varietal names have sometimes been lost. Three such Thai varieties that are seteemed in their homeland are 'Baidum', 'Biew Kiew', and 'Chompoo'.
'Kohala' - Large size, sweet, good flavor, often has an abortive small seedk, most widely planted in California and Florida. 'Wu Yuan' or 'Blackball' - Small size more acidic, vigorous tree planted in Florida. In China it is preferred as a rootstock if approach grafting is to be used
'Ship'i' - Very large size, less tasty, late season, planted in Florida.  

 

Nutrition

The longan has the following nutritional content per 1 gram of edible fruit. (Note that analyses vary depending on the fruit ripeness, variety, etc. and the values here are only a relative guide whose accuracy is approximately +/- 20%.)
calories 0.61 calories iron 0.012 milligrams
carbohydrates 0.16 grams thiamin   negligible
fats 0.001 grams riboflavin 0.005 milligrams
fiber 0.004 grams niacin   negligible
calcium 0.10 milligrams ascorbic acid 0.06 milligrams
phosphorus 0.42 milligrams beta-caritene   negligible

 

Compiled by Robert Vieth, Master Gardener