56 ARISTOCRATS OF THE GARDEN 



and thickets where climbing plants grow wild their 

 associate plants are seized upon and forced to assist 

 these climbers in rearing themselves against gravity 

 toward the sunlight. 



A majority of our hardy woody climbers, for ex- 

 ample Wistaria, Actinidia, Celastrus, climb by means 

 of twining stems. In a number the stems coil in a 

 definite direction and refuse absolutely to be cajoled 

 into twining in any other direction. For example: 

 the shoots of a common European Woodbine (Loni- 

 cera Caprifolium) twine from right to left (clockwise), 

 those of the Dutchman's Pipe (Aristolochia durior) 

 twine from left to right (counter-clockwise). The 

 why of this is outside our immediate discussion but 

 that it is fact may be proven by all who will take the 

 trouble to examine these plants. 



Another large group climbs by means of tendrils 

 which are specially modified organs. In the Grape- 

 vine (Vitis) an abortive inflorescence developed from 

 the side of the shoot opposite the leaf is the specially 

 adapted climbing organ. The closely allied Boston 

 Ivy (Parthenocissus tricuspidata) has the free ends of 

 the tendril flattened into discs which firmly adhere to 

 walls and rocks. In Smilax the stipules are modified 

 to form tendrils. In Clematis the stalk of the leaf 

 and leaflets serves the purpose. In another group to 



