SECTION 6.1 



STEMS. 



41 



93), as also the shorter ones of the Japanese species, effect the object differ- 

 ently, namely, by expanding the tips of the tendrils into a flat disk, with 

 an adhesive face. This is applied to the supporting object, and it adheres 



firmly ; then a 

 shortening of 

 tlie tendril and 

 its brandies by coiling brings np the growing 

 siioot close to the snpport. This is an adapta- 

 tion for climbing mural rocks or walls, or the 

 trunks of trees, to which ordinary tendrils are 

 unable to cling. The Ivy and Poison Ivy attain 

 the same result by means of aerial rootlets (78). 



100. Some tendrils are leaves or parts of 

 leaves, as those of the Pea (Fig. 35). The na- 

 ture of the tendril is known by its position. A 

 tendril from the axil of a leaf, like that of Pas- 

 sion-flowers (Fig. 92) is of course a stem, i. e. 

 a branch. So is one which terminates a stem, 

 as in the Grape-Vine. 



101. Spines or Thorns (Fig. 95, 96) are 

 commonly stunted and hardened branches 

 or tips of stems or branches, as are those of 

 Hawthorn, Honey-Locust, etc. In the Pear 

 and Sloe all gradations occur between spines 

 and spine-hke (spincscent) branches. Spines 



1 lay be reduced and indurated leaves ; as in the Barbcri 

 nature is revealed by their situation, undernrath an axil 



nhere theii 

 bud. Bui 



Fig. 92. A small Passion-flower (Passijfnra sicyoidcs), showing the tendrils. 



Fig. 93. Piece of the stem of Virginia Creeper, bearing a leaf and a tendril. 

 91. Tips of a tendril, about the natural size, showing the disks by which they hold 

 fast to walls, etc. 



