296 



A<;KON<>.MY 



Vacuoles, 57 



Variation, how induced, '2<>l ; results 

 of, 274 



Venation, netted, 72 ; palmate, 72 ; 

 parallel, 72 ; pinnate, 72 ; reticu- 

 lated, 72 



Verdant zone, 117 



Vines, methods of climbing, 89 



Warm-season plants, 134 



Water, amount in plant parts, 97 ; 

 amount transpired by plants, 90 ; 

 as a weathering agent, 14, 18 ; 

 capillary, 47 ; hygroscopic, 47 ; 

 percolating, 47 ; plant form and, 

 125 ; use of, to plants, 96 



Weathering, by decomposition, 13 ; 

 by disintegration, 16 



Weathering agents, 13, 17 



Weeds, distribution of, 179 ; harm- 

 fulness of, 165, 166 ; how to eradi- 

 cate, 167; less harmful, 178; origin 

 of, 164 ; sprays for, 108 



Weeds, injurious: black bindweed, 

 172; buttercup, 176; Canada this- 

 tle, 174 ; common bindweed, 172 ; 

 crab grass. 175; dandelion, 171; 

 foxtail, 176; green amaranth, 170; 

 old witch grass, 176; oxeye daisy, 

 174 ; pigweed, 170 ; plantain, 171 ; 

 prickly lettuce, 173 ; purslane. Kilt ; 

 quack grass, 175; ragweed, 173; 

 sorrel, 177; spotted spurge, 170; 

 spreading amaranth, ]<!); tumble- 

 weed, 170 ; wild carrot, 176 ; wild 

 mustard, 173 



Windbreaks, 120 



Winter annuals, 87 



Woodlands, enemies of, 213 ; value 

 of, 212 



Xenia, 268 

 Xerophytes, 125 

 Xerophytic hydrophytes, 127 



Zero, upper, middle, and lower, 115 



