SUPPLEMEN7 



(the true Nasturtium is the water cress), belongs to the Geranium 

 family, but has not so many mechanical devices. It is, however, usu- 

 ally available for out-of-door observation in California, and it is very 

 attractive and interesting, particularly in its method of climbing, and 

 its pollination. The honey in this case, too, is in a spur, which is not 

 concealed by union with the petiole. The flowers, being solitary, need 

 to be larger and to have their sepals, as well as their petals, brightly 

 colored. The honey guides are prominent, the stamens and styles 

 behave precisely like those of the larkspur, see Chapter XV. Humming 

 birds frequent the flowers and are the most efficient visitors. Bees 

 and flies sometimes come for pollen; perhaps the larger bees get 

 honey also. 



The leaf movements so common in Leguminosae and so striking in 

 Oxalis, were noted in Chapter V, but should be taken up again. It 

 should be observed especially, that these leaves assume their various 

 "sleeping" positions, all of them practically vertical, during dry 

 winds or a prolonged drought; even the filaree erects and folds its 

 leaves to some extent. Obviously, the same device that restricts radi- 

 ation of heat, also restricts transpiration of moisture. 



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