-420 



GENERAL REVIEW. 



Vanilla.* Orchidaceous Plants from the West Indies and 

 tropical America, of scandent habit, easily propagated by 

 division. V. planifolia yields the " vanilla " of commerce, one 

 of the rarest and most valuable of spices. Dr Morren of 

 Liege was the first to prove, experimentally, that the fruit of 

 Vanilla may be produced as freely in our own hothouses as in 

 Mexico. In the year 1836, a plant in the Botanic Garden of 

 Liege produced fifty-four flowers, which, being artificially fecun- 

 dated, produced the same number of pods equal to those 

 brought from Mexico. In 1837, a fresh crop of about one 

 hundred was obtained from another plant, by the same means. 



He attributes the fecundation of 

 the plants in Mexico to the ac- 

 tion of some insect which fre- 

 quents the flowers, and hence 

 accounts for the non-production 

 of fruits in those plants which 

 have been introduced into other 

 countries. 



This plant has fruited freely in 

 the stoves at Osberton, Notts, 

 and Mr Bennett thus describes 

 his method of procedure : "I 

 attribute failure in the bloom- 

 ing to not getting the wood well 

 matured, for if it is not well har- 

 dened it will not flower freely. 

 I allow my plant at times to get 

 almost dry and parched." The 

 failure in the production of fruit 

 arises from a want of knowledge 

 of the art of fertilising the stig- 

 ma, an operation which requires 

 both care and skill. In the 

 flowers of the Vanilla, besides the sepals and petals, there is 

 the column which bears the anther and stigma. The anther (a) 

 is a dilated appendage attached to the summit of the column 

 (clinandrium) by a narrow curved neck, and contains the pol- 

 len-masses (pollinia) within a cavity on its lower surface. This 

 appendage, by means of its curved neck, bends downwards 

 towards the lower surface of the column, where it rests upon 

 an organ called the rostellum (r), interposed between the 



* See a paper "On the Cultivation of 'Vanilla in Mauritius," by John 

 Home, communicated by Dr Hooker to the. 'Jour. Hort. Soc.,' vol. ii. 

 (New Series), p. 61. 



Column of Vanilla flower, front 

 and side views, a, Anther-case ; r, 

 Rostellum ', 2, Stigmatic cavity. 



