FORESTRY OF WEST AFRICA. 421 



Hydrocharide.e. 



Vallisiuria spiralis, L. — Aquatic perennial herb 

 used in India by sugar refiners. The sugar is covered 

 with a layer of the leaves, and the moisture from them 

 drains slowly through the sugar, carrying with it the 

 dark-coloured masses. Every several days the leaves 

 are replaced by fresh ones, until the whole mass is 

 refined, when it is dried in the sun. — ' Useful Plants 

 of India,' Drury, p. 374. 



Distribution : Upper Guinea. 



ORCHIDE^. 



Vanilla planifolia, And. — The Kew Museum con- 

 tains a bracelet said to be made of the roots of this 

 plant, which is also the source of the vanilla pods of 

 commerce. It was collected by Gustav Mann in 

 West Tropical Africa. 



SCITAMINE^. 



Turmeric {Curcuma longa, L.). — Perennial herb. 

 The rootstock or tubers form the turmeric of commerce, 

 of which there are two sorts, known as the round and 

 the long ; but both are the produce of the same plant. 

 Turmeric is not now used as a remedial agent, but is 

 introduced into the Pharmacopoeias as a test of the 

 presence of alkalis. It is also employed as a condi- 



