Opinions differ regarding the value of the longan. It is popular among the Chinese, but Americans who have tested longans produced in California and Florida have not as a rule considered them good. Frank N. Meyer says that they are improved by cooking, and that preserved longans are considered by some superior to preserved litchis, the flavor being thought more delicate.
According to Alphonse DeCandolle, the longan is a native of India, whence it has been introduced into the Malay Archipelago, southern China, and (recently) tropical America. It is a tree 30 to 40 feet high, resembling the litchi in habit and appearance. The leaves are compound, with two to five pairs of elliptic to lanceolate, glabrous, glossy, light green leaflets. The flowers are borne in terminal and axillary panicles, and are small and unattractive. The fruit is round, an inch or less in diameter, light brown in color, with a thin shell-like outer covering, and white flesh (aril) similar in character to that of the litchi but less sprightly in flavor. The single seed is dark brown and shining.
Meyer says: "The fruit, which is naturally brown, is generally artificially changed to a chrome-yellow. It is eaten fresh, canned, or dried. In the last condition one can obtain it at the Chinese New Year time in the most northern cities of the Empire. There are several varieties of longans, differing in size of fruit, productivity, and size of kernel. Their northern limit of growing seems to be, like that of the litchi, the region around Foochow."
Analysis of the longan by Alice R. Thompson has shown the ripe fruit to contain: Total solids 17.61 per cent, protein 1.41, total sugars 8.34, fat 0.45, and fiber, 0.63.
In French, the longan is commonly termed ceil de dragon (dragon's eye). The Chinese name is spelled alternatively longyen, long an, lung an, lingeng, and so on. Botanical synonyms of Euphoria Longana are Nephelium Longana, Cambess., and Dimocarpus Longan, Lour.
In southern California and in southern Florida, the longan thrives and fruits abundantly if planted in situations not subject to severe frosts. It withstands lower temperatures than the litchi and is less exacting in its cultural requirements. P. D.
Barnhart, writing in the Pacific Garden, says of its culture in California: "We are of the opinion that the greatest success may only be obtained with it in the warmer foothill sections of the country, and that, too, beneath the sheltering arms of live oaks. It seems necessary to protect it from the direct sunlight and desiccating atmosphere of our summers, as well as from the frosts of winters. It requires an abundance of water during the summer months." It has been much more successful on the shallow soils of the Miami region in southern Florida than its relative the litchi.
Propagation is by seed, layering, and grafting, as with the litchi. Higgins remarks concerning the habits of the tree: "The statement has been made that it is a slower grower than the litchi, but this certainly does not hold true under Hawaiian conditions, where it is a robust tree far exceeding the litchi in vigor and rapidity of growth. As in the case of the litchi, seedlings frequently are very tardy coming into bearing." In southern China, where the longan is extensively grown, it is said to require more pruning than the litchi.
The fruit ripens somewhat later than that of the litchi, and is popular among the Chinese, quantities of it being sold in Hongkong and Canton during late summer. Doubtless some of the varieties cultivated in China are superior in quality of fruit to the seedlings which have been grown in the United States. It has been the general opinion of those who have tasted the American-grown longan that it is insipid and somewhat mawkish, although Barnhart considers it excellent.