Chap. L TWINING PLANTS. 41 



when we reflect how little the leayes are developed on 

 the young and thin revolying internodes. It is all 

 the more remarkable, as botanists beliere (Mohl, 

 p. 119) that twining plants are but little sensitive 

 to the action of light. 



I will conclude my account of twining plants by 

 giving a few miscellaneous and curious cases. With 

 most twining plants all the branches, however many 

 there may be, go on revolving together; but, ac- 

 cording to Mohl (p. 4), only the lateral branches of 

 Tamils elephantipes twine, and not the main stem. 

 On the other hand, with a climbing species of Aspa- 

 ragus, the leading shoot alone, and not the branches, 

 revolved and twined ; but it should be stated that the 

 plant was not growing vigorously. My plants of 

 Comiretum arffenteum and C. ptirpureum made nume- 

 rous short healthy shoots ; but they showed no signs 

 of revolving, and I could not conceive how these 

 plants could be climbers ; but at last C. arffenteum put 

 forth from the lower part of one of its main branches 

 a thin shoot, 5 or 6 feet in length, differing greatly 

 in appearance from the previous shoots, owing to its 

 leaves being little developed, and this shoot re- 

 volved vigorously and twined. So that this plant 

 produces shoots of two kinds. With Periploca Grseea 

 (Pahn, p. 43) the uppermost shoots alone twine. 

 Polygonum convolvulus twines only during the middle 

 of the summer (Pabn, p. 43, 94) ; and plants growing 

 vigorously in the autumn show no inclination to 



climb. The majority of Asclepiadaceae are twiners ; 

 a 



