PLATE XX. 



Fig. 38. Vascular bundle from the stem of A', pennsylvanicum: x 140. 

 A, wood fibers; B, phloem; C, bast; Y, tracheal vessels; Z, wood pa- 

 renchyma. 



Fig. 39. Vascular bundle from the stem of X. americanum. x 133. 

 D, tracheal vessel; E, wood fibers; F, wood parenchyma; G, phloem; //, 

 bast. 



Fig. 40. Vascular bundle from the stem of X. globosum. X 140. 1, 

 tracheal vessels; J, wood parenchyma; K, wood fibers; L, phloem; M, bast. 



Fig. 41. Cross section of portion of two bundles of stem of X. globo- 

 sum. X 43. N, elongated ray cells. 



Fig. 42. Cross section of base of bundle of X. americanum. x 193. 

 0, tracheal vessel; P, lignified cells. 



Fig. 43. Longitudinal section of wood parenchyma from X. globosum. 

 X 193. 



Fig. 44. Wood fibers from X. globosum. X 193. 



Fig. 45. Tracheal elements in stem of X. pennsylvanicum. X 200. 



Fig. 46. Tracheal elements in stem of X. globosum. x 200. 



Fig. 47. Tracheal elements in stem of X. americanum. X 200. 



Fig. 48. Wood fibers from X. americanum. x 193. 



