There are also the Palmera (Borassus flabelliformis) of Southern India, and the Nipa (Nipa fructicans) of the Philippines. Either of these could undoubtedly be made profitable sugar producers. The latter is used commercially only as a source of alcohol.
There is practically no limit to the number of sacchariferous plants one might name in the Tropics and subtropics, but many of these do not contain a sufficient percentage of sucrose, or else they contain such a high percentage of impurities that the low yield of sugar and the high cost of manufacture make their use unprofitable.
By P. J. Wester, Horticulturist in Charge of Lamao Experiment Station.
De Candolle, in his "Origin of Cultivated Plants," discusses 5 species belonging to the genus Citrus: The pomelo, C. decumana L.; the citron, lemon, and lime, here considered as distinct species, which he includes under the one species, C. medica L.; the sweet orange, C. aurantium L., which he separates from the sour orange and which is also by him considered as a distinct species, C. vulgaris Risso; and finally the mandarin, C. nobilis Lour. Of these, the pomelo, orange, mandarin, lemon, lime, and citron are important pomologically, the sour orange being grown principally as stock for the other species.
The pomelo is by the same author considered to be indigenous to the Pacific Islands east of Java, the citron and affiliated species to have originated in India, and the sour orange east of India, and all to have been in cultivation for over two thousand years. The antiquity of the orange and mandarin is less, both species being from China and Cochin China.
All these species have been introduced into the Philippine Archipelago, and are well distributed excepting the sour orange, which is rarely seen. The discussion of all species refers to them as found in the Philippines except when otherwise stated.
No very distinct types are found among the oranges or mandarins; the variation in the pomelo is considerable, although, so far as the writer has noted, scarcely enough to warrant the distinction of separate varieties. Both the white and red-fleshed types occur with many gradations, but no studies have been made to note which other correlative characters, if any, are identified with these different forms. The very primitive pomelos (Pl. II, c) that are not infrequently seen in cultivation might indicate that this species is indigenous to the Philippines, though so far as the writer knows the tree has never been seen in the virgin forest. Closer observations have been made on the general type represented by the citron, including the lemon and lime, and several distinct forms have been recognized.