266 



ELEMENTARY STUDIES IN BOTANY 



branches to extend over an extraordinary area. There is 

 record of a banyan cultivated in Ceylon with 350 large and 

 3000 small prop-roots, and able to cover a village of one 

 hundred huts. The mangrove is found along tropical and 

 subtropical seacoasts, and gradually advances into the shal- 



FIG. 228. A screw-pine with prop-roots. Photograph by LAND at Orizaba, Mexico. 



low water by dropping prop-roots from its branches and 

 entangling the detritus (Fig. 229). 



(2) Water-roots. If a stem is floating, clusters of whitish 

 thread-like rootlets usually put out from it and dangle in the 

 water. Plants which ordinarily develop soil-roots, if brought 

 into proper water relations, may develop water-roots. For 



