I'M) EFFECTS OF WEATHER CHAP. 5. -2. 



with regard to other vegetables, which open 

 and shut their blooms at stated hours of the 

 day, or at certain distances of time before 

 changes of weather. In these latter cases we 

 must look for some other cause of the phaeno- 

 menon, perhaps to some electrical changes in 

 the state of the atmosphere. In order, however, 

 that facts may precede theory, I shall first notice 

 few of the particular phaenomena. 

 TheHeliatithus an mius exhibits a phaenomenon 

 which we can most clearly ascribe to the solar 

 rays; namely, that of turning its flowers to- 

 wards the sun ; being directed Eastward in the 

 morning, South at noon, and Westward in the 

 evening. Tire name of Sunflower has, however, 

 no connexion with this circumstance. 



The generality of flowers open at sunrise, and 

 close in the evening. 



The Evening Primrose, Oenothera liennis, 

 opens at sunset, and closes before midnight. 



Most of the syngenesious plants are periodi- 

 cal, and have certain times of day for opening 

 and shutting. 



The Tragopogon pratensis, or Yellow Goats- 

 beard, opens in the morning, and shuts at 

 noon. The Tragopogon porrifoJlus does the 

 same. 



