360 INDEX. 



Believed to be a component in almost 



every part of the vegetable . . . 227 



Vegetable matters, very similar in their analysis — such as 

 gum, olive oil, and resin. — The solid components also 

 very similar in their composition . . . 249 



Vernonia, the genus of, and some of the species . 155 



Vervain (Verbena), the generic character . . 129 



Vetch (Viccia), the generic trait . . . 155 



Violet (Viola), the genus of . . .74 



Viper's-bugloss (Echium), the genus of 67 



W. 

 Wake-robin (Arum), the genus of ... 196 



Wall-cress (Arabis), the genus of . 139 



Wall-flower and Stock (species of Cheiranthus), examined 7 



■ (Cheiranthus) the genus of . • 139 



the remarkable number and disposition of the 



stamens . . . . . . 7, 8 



Wallnut (Juglans), the genus of . . . 194 



Water-Plantain (Alisma), how known . . 93 



Wax-myrtle, Gale (Myrica), the genus of '. • 202 



Wild Indigo, a papilionaceous flower with 10 distinct sta- 

 mens ...... 13 



(Baptisia), its generic character . . 101 



Wild Rice (Zizania), the genus of . . 192 



Willow (Salix), the genus of . . .200 



Winter-green (Pyrola), related to Monotropa . 107 



Witch-hazel (Hamamelis), the genus of . . .63 



Wheat (Triticum), how known, as a genus . . 55 



Whitlow-grass (Draba), disposition of the cotyledones in 



the Crucifer.* , 138 

 Whortleberry (Vaccinium), how distinguished . 106 

 Woad (Isatis), the genus of . . . .140 

 Wood concentric and divergent layers of . . 262 

 concentric layers and depositions in the woody tex- 

 ture — that of silex in the Teak wood . . 263 



divergent layers — soluble on maceration in water — 



supposed to be processes from the pith, or medullary 

 rays, though many are not traceable to the pith 264 



Wood while in the state of alburnum, endowed with 



irritability ; but in time loses its vitality . ib. 



, its zones annually renewed ; — origin of; deposited 



by the bark, from the sap, after its elaboration in the 

 leaves. Experiments to prove this fact . . 265 



Y. 



Yew (Taxus), the genus of . 208, 209 



Z. 

 Zinnia, the genus of, with species . 127 



