TURNING OF FLOWERS TO THE LIGHT. in 



Nor is this effect of light peculiar to leaves alone. 

 Many flowers are equally sensible to it, especially the 

 compound radiated ones, as the Daisy, Sun-flower, Mar- 

 igold, &c. Ii> their forms Nature seems to have de- 

 lis-hted to imitate the radiant luminary to which they are 

 apparently dedicated, and in the absence of whose beams 

 many of them do not expand their blossoms at all. The 

 stately Annual Sun-flower, HeUanthus anmms, displays 

 this phoenomenon more conspicuously on account of its 

 size, but many of the tribe have greater sensibility to 

 light. Its stem is compressed in some degree, to facili- 

 tate the movement of the flower, which, after following 

 the sun all day, returns after sun-set to the east, by its 

 natural elasticity, to meet his beams in the morning. 

 Dr. Hales thought the heat of the sun, by contracting the 

 stem on one side, occasioned the flower to incline that 

 way ; but if so, it would scarcely return completely at 

 night. There can be no doubt, from the observation of 

 other similar flowers, that the impression is made on 

 their radiated florets, which act as wings, and seem con- 

 trived chiefly for that purpose, being frequently destitute 

 of any other use. A great number of leaves likeuise 

 follow the sun in its course ; a clover-field is a familiar 

 instance of this. 



Of all leaves those of pinnated leguminous plants are 

 found most affected by light, insomuch that it appears, 

 in several cases, the sole cause of their expansion, for 

 when it is withdrawn they fold over each other, or 

 droop, as if dying ; and this is called by Linnasus the 

 Sleep of Plants, who has a dissertation on the subject in 

 his Ammnitates Academic^e. The term Sleep may not 



