U NOTES ON DIPTEROCARPS. 



This dying back of Sal seedlings is most intense in the rains ; 

 the seedling in appearance dies back exactly as it does also from 

 drought, as if the plethora of water at the roots works in the same 

 way as its want. But Sal seedlings can be grown in water cultures, 

 and therefore contact with water itself has nothing to do with it. 

 It would rather seem to be something shut out from or brought to 

 the roots (Hole's toxic body for instance) by the water. Death can 

 be caused in pots without the neighbourhood of other plants, and 

 and therefore by no toxic excretion of another plant (Hole in 

 Indian Forester, 1916, p. 337). The Malayan Shoreas too die in 

 wet periods, as far as I have observed, but there is this difference 

 that Sal dies back only, whereas they die out. Herein is a difference 

 between the two, perhaps connected with the greater success of the 

 Sal (within its area), — a difference which demands investigation. 



For the purpose in hand, namely to form a sound classifica- 

 tion of the order to which these trees belong, two facts may be 

 useful, (i) that the Indian species 8. robusta and 8. obtusa, 

 are more able to make pure forests than any of our many Malayan 

 Shoreas, and (ii) that 8. robusta, at any rate, is in its seedling more 

 similar to the genus Diptero carpus which also forms pure forests, 

 than are the Malay Shoreas, 8. leprosula, Miq., 8. rig Ida, Brandis, 8. 

 macroptera, Dyer, S. bracteolata, Dyer, and 8. gibbosa, Brandis. 

 The pure forests are not the creation of man through, firing: but 

 the mixed forests may carry his impress. 



Jour. Straits Branch 



