56 SYLVICULTURE IN THE TROPICS 



PT. I 



accrescent calyx lobes, giving the fruit the appearance 

 of a shuttlecock. These wings help in the dispersal of 

 the fruit by the wind, and also act as parachutes to 

 prevent the delicate radicle, which often protrudes from 

 the fruit before it becomes detached, from being injured 

 by its fall on the ground. Other trees provided with 

 very similar appendages for their fruit are Gyrocarpus, 

 (Combretaceae), Lophira (Ochnaceae), and Monotes 

 (Tiliaceae ?), while a large number of Combretaceae 

 have two to five costal wings on their fruit. Among 

 the Leguminosae the Dalbergia has light, indehiscent 

 legumes which get blown away to some distance, while 

 the Pterocarpus has its larger one seeded legume disc- 

 shaped and edged with a continuous wing. In 

 Daniellia and Cyanothyrsus the seed, which is attached 

 by a filiform process to a dehiscent legume, carries away, 

 in its fall, portion of this legume, which is thin and 

 membranous and acts as disperser and parachute. 

 Among other winged fruits may be mentioned that of 

 Securidaca (Polygalaceae), Berry a (Tiliaceae), and the 

 hairy umbrella-like parachutes of the Compositae and 

 other appendages of several shrubs and climbers. In 

 other trees it is not the fruit but the seed which is 

 provided with winged or silky appendages for its 

 dispersal ; such are several of the Malvaceae (Bombax, 

 Eriodendron, and Gossypium), Pterospermum (Ster- 

 culiaceae), many of the Meliaceae (Swietenia, 

 Chloroxylon, Khaya, Chickrassia, Azadirachta, Ced- 

 rela, etc.), several Apocynaceae (Funturnia, Adenium, 

 Holarrhena, Alstonia, etc.), the Asclepiadeae, most 

 Bignoniaceae (Stereospermum, Millingtonia, Oroxylum, 

 etc.), and the Salicineae. As many of the genera 

 mentioned have great economic importance the study 

 of the dispersal of their seed is of much interest to the 

 forester. 



The effect of winds on loose sandy soils or, in dry 

 countries especially, on soft sandstone formations is 

 exemplified by the formation of dunes and sand-drifts. 

 The term " dune " is more particularly applied to the 



