12 \ ■ PLANTS 



the ink rise in the vascular bundles? d. A prepared slide under 

 the hand lens showing the vascular bundles and the vessels. Draw 

 one bundle X25. 



54. The leaf: a. Surface view of the epidermis of a leaf showing the sto- 

 mata (prepared slide, microscope), b. Cross section of the leaf 

 (prepared slide, microscope). Identify the layers found in 18. 



IX. MODIFIED STRUCTURES 



Modified Roots 



55. Fibrous roots (grasses). 



56. Enlarged (storage) roots. 



. (a) Enlarged tap-root (turnip). 



(b) Enlarged fascicled roots (Dahlia). 



(c) Enlarged lateral roots (sweet potato). 



57. Prop roots (corn). 



58. Aerial roots as holdfasts (ivy). 



Modified Stems and Branches 



(In each case note the nodes and internodes and the character of the 

 leaves and buds.) 



59. Procumbent stems (periwinkle). 



60. Runner or stolon (strawberry). 



61. Underground stems: 



(a) Rootstock (Smilax). 



(b) Rhizome (Solomon's seal). 



(c) Tuber (Irish potato). 



(d) Corm (Jack-in-the-pulpit). 



62. Climbing stems: 



(a) Twining stems (morning glory). 



(b) Climbing by spiral tendrils (grape). 



(c) Climbing by adhesive tendrils (Virginia creeper). 



(d) Climbing by aerial roots (ivy). 



63. "Stemless" plants: 



(a) Study a plant of salsify. Is there a stem? Where does the root 

 begin? Note the leaf scars. 



(b) Make a longitudinal section of root and stem. Note distribution 

 of pith and vascular bundles. 



(c) Make cross sections of the stem and the root. Note again as in b. 



(d) Compare a beet or turnip with the salsify as in a, b and c. 



