PLATE XVI. 



Fig. 1. Tangential section of leaf of A. pennsylvanicum. x 200. A, 

 border parenchyma cells; B, tracheal vessels; C, photosynthetic tissue. 



Fig. 2. Tangential section of leaf of A. globosum. X 200. D, border 

 parenchyma cells; E, tracheal vessels, F, photosynthetic tissue. 



Fig. 3. Tangential section of leaf of X. americanum. X 200. C, bor- 

 der parenchyma cells; H, tracheal vessels; /, photosynthetic tissue. 



Fig. 4. Cross section of leaf of A", americanum. x 193. J, epidermis; 

 K, tracheal vessels; L, border parenchyma cells; M, photosynthetic cells; 

 N, vascular bundle; O, trichome. 



Fig. 5. Photosynthetic cells from the leaf of A. pennsylvanicum. X 193. 

 Fig. 6. Smaller photosynthetic cells from the leaf of A. pennsyl- 

 vanicum. x 193. 



Fig. 7. Photosynthetic cells from the leaf of A. Globosum. X 193. 

 Fig. 8. Photosynthetic cells from the leaf of A. americanum. X 193. 



Fig. 9. Cross section of leaf of X. pennsylvanicum. X 193. P, stoma; 

 Q, epidermis; R, vessels; S, water-storage cells; T, vascular bundle; U, 

 trichome from leaf. 



