132 



BEGINNERS' BOTANY 



Examples are bean, morning-glory. The hop twines from 



left, or with the sun. 



the observer's right to his 



Fig. 172. ^ - Clematis climbing by Leaf-tendril. 



Suggestions. — 136. Set the pupil to watch the behaviour of any 

 plant that has tendrils at different stages of maturity. A vigorous 

 cucumber plant is one of the best. Just beyond the point of a young 

 straight tendril set a stake to compare the position of it. Note 

 whether the tendril changes position from hour to hour or day 

 to day. 137. Is the tip of the tendril perfectly straight? "Why? 

 Set a small stake at the end of a strong straight tendril, so that the 

 tendril will just reach it. Watch and make drawing. 138- If a 

 tendril does not find a support what does it do? 139. To test the 

 movement of a free tendril draw an ink line lengthwise of it, and 

 note whether the line remains always on the concave side or the 

 convex side. 140- Name the tendril-bearing plants that you know. 

 141. Make similar observations and experiments on the tips of 

 twining stems. 142. What twining plants do you know, and which 

 way do they twine? 143. How does any plant that you know 

 shoot up? 144- Does the stem of a climbing plant contain more 

 or less substance (weight) than an erect self-supporting stem of 

 the same height? Explain. 



