304 



RHIZ0PH0REAE. 

 Rhizophora, Linn. 



Rhizophora racemosa, E. Mey ; Fl. Trop. Afr. II. p. 408. 



III. — Arb. Amazon (1900) t. 15 {R. Mangle, var. racemosa, habit). 



Vemac names. — Egba (Yoruba, Thompson) ; Egba or Igi-Egba 

 (Lagos, Dawodu) ; Manko, Mangi (Gambia, Dudgeon) ; Encle, Koghia- 

 bera, Ntague (Ivory Coast, Chevalier). Red Mangrove. 



Brass (Barter, No. 1850, Herb. Kew) ; Akassa (Barter, No. 2078, 

 Herb. Kew) ; Lagos (Millen, No. 137 ; Dawodu, No. 329) ; Banks of 

 the Nun (Mann, No. 492, Herb. Kew) ; throughout West Africa 

 extending to Angola and Loanda, S.W. Africa, along the banks of 

 rivers up to the limit of tidal influence ; and occurring under similar 

 conditions in tropical America and the West Indies. 



The American Mangrove {Rhizophora Mangle, Linn.), may also 

 extend to West Africa, but there are no satisfactory specimens at Kew 

 to make certain of this point. 



The other Old World Mangroves {Rhizophora mucronata, Lam. ; 

 Fl. Trop. Afr. ii. p. 407, and Ceriops Candolleana, Arn. ; Fl. Trop. 

 Afr. ii. p. 409— known in Malaya as " Tengah ") appear to be con- 

 fined in Africa to the east coast. 



The conditions of growth, general habit and uses of all three, 

 however, are much the same. 



The bark contains tannin, but the quality and action is somewhat 

 uncertain, and no demand has arisen for the West African product. 



Efforts to create a trade in the bark from West Africa have 

 invariably failed, owing usually to the low percentage of tannin, poor 

 and uncertain quality, and unremunerative rates. A promising 

 industry in Senegal was stopped by law, because the destruction of 

 the Mangrove forests was thereby threatened. 



Bark from Sierra Leone has been found to contain 18 per cent, of 

 tannin, Gambia 25 per cent., Gold Coast 29 per cent. (Bull. Imp. Inst. 

 1907, pp. 347, 348), Cameroon s 20 to 27 per cent. — calculated on air 

 dried bark containing from 10*6 to 14*6 per cent, of moisture (I.e. 

 1906, p. 06), Loanda 15'7 per cent. — bark from old wood (Cons. Rep. 

 Ann. No. 3478, 1905, p. 4), and from S. Nigeria 16*8 per cent. (Gov. 

 Gaz. S. Nig. 21st June, 1911, Suppl. p. 10). 



Good bark should contain 45 per cent, and upwards of tannin, and 

 other characters being equal this would probably realise, at the 

 present time, not more than from £4 to £6 per ton. 



Rhizophora mucronata is the best species for the production of 

 suitable tanning bark, and the commercial supplies come chiefly 

 from East Africa, Zanzibar and Asiatic sources. 



The bark soon deteriorates if allowed to get wet or fermented 

 after gathering, and the unsatisfactory condition of West African 

 bark may be due to these causes. The difference in the species, 

 however, appears to be the primary cause of failure, as samples from 

 British Guiana (Bull. Imp. Inst. 1907, p. 346), Jamaica, Bahama and 

 other West Indian Islands (Kew Bull. 1892, p. 227 ; Agric. News, 

 Barbados, v. 1906, p. 252), have met with the same fate as those from 

 West Africa, and no successful contributions have come from 

 America, where R. racemosa and R. Mangle predominate. 



The best mangrove bark or extract is not so acceptable to tanners 

 as oak bark, Valonia, Quebracha, Mimosa bark, and other well-estab- 

 lished tanning materials. The principal objection lies in the deep 



