STEMS 57 
74, Tendril-Climbers. —The plants which climb by means 
of tendrils are very interesting subjects for study, but they 
cannot usually be managed very well in the schoolroom. 
Continued observation soon shows that the tips 
jof tendrils sweep slowly about in the air until 
they come in contact with 
some object about which 
they can coil themselves. 
After the tendril has taken 
a few turns about its sup- 
port, the free part of the 
tendril coils into a spiral 
Fic. 29. Coiling of gynd thus 
Petiole of Dwarf 
Tropzolum. 
1 
draws the~ 
whole stem 
toward the point of attachment, as shown jj 
in Fig. 28. Some tendrils are leaves or 
stipules, others are modified stems. 
75. Twiners.1— Only a few of the 
upper internodes of the stem of a twi- 
ner are concerned in producing 
the movements of the tip of the 53 HL asm (e~ 
stem. This is kept revolving in A ! eS 
an elliptical or circular path un- 
til it encounters some roughish 
and not too stout object about 
which it then proceeds to coil il 
itself. The direction of the coil- Fic. 30. Twining Stem 
ing varies in different kinds of of Hop. 
climbers, some following the course shown in the figure 
1 See article on Climbing Plants, by Dr. W. J. Beal, in the American Nat- 
uralist, Vol. LV, pp. 405-415. 
