20 REPRESENTATIVE PLANTS 



Street trees. Determine the trees that are found growing 

 along the streets, and the relative abundance of each kind. 

 Seek an explanation for the abundant planting of a few 



varieties. 



3. Climbing Stems 



Material. Material for this study may be found com- 

 monly in woodlands, or lacking such sources, the vines of the 

 flower garden and lawn may be drawn upon. If possible, 

 however, honeysuckle and bittersweet, Virginia creeper and 

 grape, besides herbaceous climbers, should be studied. 



Twiners. Examine the twining stems of honeysuckle and 

 hitiersiceet . Compare their stem diameters with their length 

 of vine. How does the proportion compare with the simi- 

 lar measurement of upright shrubs ? Why do these plants 

 twine ? 



Holding the entwined stem with its upper end toward you, 

 observe the direction in which the stem twines. Does it 

 twine with (from left to right) or contrary (from right to 

 left) to the hands of a watch or clock ? Do both kinds of 

 vines, named above, twine in the sanie direction ? 



Draw each vine and designate direction of twining. 



Study other forms, if obtainable, in the same manner. 



Tendril bearers. Examine grape or Virginia creeper and 

 observe the coiled, slender branches (tendrils). Study, if 

 possible, material showing all ages of tendrils. Observe a 

 double effect of the coiling of the tendril. How do the 

 tendrils of the two vines differ ? How are the tendrils ar- 

 ranged with reference to buds ? Discover, if possible, 

 other vines that have similar tendrils. 



Draw the tendril and adjacent stem of such specimens as 

 you have. 



What advantage, if any, does either form of climber pos- 

 sess? 



Air roots. Study a stem of the poison ivy (inclosed in a 

 bottle). What structure does this vine have to enable it to 



