VANILLA 37 



Mr. Dupont of the Botanic Gardens there gives an 

 interesting account of some experiments in manuring 

 which are worth quoting. In five beds the plants were 

 grown in ordinary soil, in the others (fifteen) the orchid 

 was planted in fibrous roots of the common fern, 

 Gleichenia dichotoma, a fern which to a large extent 

 in most tropical countries takes the place of the bracken. 

 Eighteen months had elapsed since the vanilla cuttings 

 were planted. 



They are at present fully grown vines, and those which 

 were planted in ordinary soil have developed much less than 

 those which were grown from the beginning in fern roots. A 

 few of the former possess a yellowish appearance, which is 

 striking even in wet weather. In all the basins in which the 

 vanilla is growing the roots have developed alongside the walls, 

 none having extended as much as one foot from the plants 

 towards the centre of the basins. The cuttings had sprouted 

 in the proportion of 62'5 per cent in fern roots and of 27 per 

 cent in ordinary soil, on the 16th December, or three months 

 after planting. In March 1905 the shoots were 2 ft. long 

 in the basins containing fern roots, and only 6 in. in the 

 others. It was decided at that time to put a small quantity of 

 fern roots on the surface of the basins containing ordinary soil, 

 in order to accelerate the growth of vines growing in them. 

 In August all the vines were well developed, but on examina- 

 tion of the roots it was found that none went deeper than 

 6 in. in fern roots, and that in ordinary soil they were fewer 

 in number, shorter, and many of them sun-burnt. The aerial 

 roots on reaching the soil were found to make excellent growth 

 and to produce many rootlets. For this reason it seems that 

 much importance should be attached to strengthening and 

 protecting the signs of life in the lower part of the cutting. 

 In an ordinary plantation the vines are in great numbers found 

 dead or sun-burnt at the base, together with all the roots which 

 were produced on that part of the cutting. When this is the 

 case the vines produce aerial roots which replace the subter- 

 ranean ones, but much of the energy of the plant is lost in this 

 new production of roots, and the flowering delayed. 



The action of the sun on the roots is so striking that, in a 

 second series of basins to repeat the experiments which are 

 found successful in the first, I noticed that the growth of the 

 vine is checked when the layer of good loose or fibrous soil is 

 less than 2 in. deep. Under these circumstances it seems 



