230 TROPICAL AGRICULTURE 



danus in this respect. In harvesting the mangrove as a source 

 of tannin the bark is stripped, dried, and packed in bales for 

 shipment. Mangrove bark yields about 40 per cent, of tannin. 

 The bark also yields a form of cutch. The United States im- 

 ported 5,500 tons of mangrove bark in 1914. Extensive areas 

 of swamp land in the Philippines are covered with mangrove 

 trees, and a beginning has been made in harvesting this bark for 

 tannin. Similar large areas of mangrove swamps occur also 

 in Malaya. 



WATTLE BARK 



Wattle bark as a source of tannin is obtained from Acacia 

 decurrens and various other species of the same genus native 

 to Australia. These trees are also cultivated in India, Ceylon, 

 Hawaii, Natal, and various other parts of the Tropics. The 

 seeds are grown in nurseries and the young seedlings are then 

 transplanted at distances of 6 to 12 feet apart both ways. The 

 young trees are occasionally pruned in order to encourage the 

 development of straight trunks. The trees may be cut and the 

 bark stripped off at the age of 5 or 6 years, but the highest 

 percentage of tannin in the bark is obtained at the age of 10 

 years or older. At this time the bark contains 40 per cent, 

 tannin. On an average an 8-year-old tree will yield about 25 

 pounds of dried bark, while the yield from a fully mature tree 

 is about loo pounds. Wattle bark is also sometimes called 

 mimosa bark. It is much used, especially in tanning sole 

 leather. Wattle trees are short lived, and in order to secure 

 the greatest harvest of bark the trees should be cut at the age 

 of 10 to 15 years. 



QUEBRACHO 



Quebracho extract and bark has recently assumed unusual 

 importance as a tanning agent. The commercial product is 

 obtained from a large tree (Loxopterygium lorentzvi) of South 

 America, particularly Brazil and Argentina. The wood of the 



