28 



could withstand. Its clam-shell-like leaves exhibited marked 

 xerophytic movements (upward movements due to a partial loss 

 of turgor on the side towards intense sunlight), although of much 

 less intensity than in the Canavalia. In the earl}' morning the 

 leaves of Ipomoea were flat but soon after the sun began to grow 

 stronger, the halves of the leaves folded upwards, assuming an 



^-M?^- '' 





Fig. 2. Canavalia lineata on the strand, Taal \'ol?ano, P.I. (April 19, 1914- 

 9:30 A.M.) 



angle of from 30 to 45° from the vertical. Stomates were present 

 in larger numbers on the upper surfaces of the leaves and when- 

 ever tested during the daytime were open. The leaves might at 

 times be less turgid, but at no time appeared really wilted. 

 With the coming of dawn the leaflets of Canavalia spread out flat 

 and the stomates opened wide. As the sun became hotter, the 

 two lateral leaflets folded together upwards in a nearly vertical 

 position, while the terminal leaflet turned up and folded on its 

 midrib, partially enclosing the lateral leaflets. The leaflets were 

 often quite limp throughout the day and the stomates became 

 closed very tight soon after limpness was apparent. Often this 

 period of closure lasted from about 9 in the morning until 3 or 

 4 in the afternoon. 



In slight shade, a condition which Canavalia can endure very 

 much better than Ipomoea, all of these reactions were less pro- 

 nounced as the conditions were less intense. 



College of Agriculture, University of the Philippines, 

 Los B.\xos, P. I. 



