TWINERS AND CLIMBERS. 191 



instance has been recorded in another plant. This 

 was Ceropegia Gardno-i, a tropical Asclepiad. The 

 top was allowed to grow out almost horizontally to 

 the length of 3 1 inches. This shoot had three long 

 internodes terminated by three shorter ones. The 

 whole shoot revolved in a direction opposite to the 

 course of the sun, and therefore in a contrary direc- 

 tion to the hop, occupying from five hours and a 

 quarter to six hours and three quarters in each revo- 

 lution. On account of the great length of this shoot 

 the circle through which it moved was about 5 feet 

 in diameter, or 16 feet in circumference, and the apex 

 travelled through this circle at the rate of 32 or 

 33 inches per hour. " The weather being hot," Mr. 

 Darwin writes, " the plant was allowed to stand on 

 my study-table ; and it was an interesting spectacle 

 to watch the long shoot sweeping this grand circle, 

 night and day, in search of some object round which 

 to twine." 1 



The greater number of twining plants climb m a 

 direction opposed to the course of the sun. The hop 

 and the bryony pursue the same course as the sun. 

 The bean {Phaseohis vulgaris), purple convolvulus, 

 and great white convolvulus, follow a course opposed 

 to the sun. The bitter-sweet {Solmium dtilcamara), 

 which is a poor climber, turns in both directions. Of 



1 Darwin, " Movements of Climbing Plants," p. 6. 



