Tobosa grass. See Hilaria 



Tolerance, 14, 15, 16 



Topography, 171 

 and frequency, 112 



Toxins, 37 



Trace elements, 12 



Tragopogon pratensis (Goatsbeard), 97 



Transitions in vegetation, 68, 138, 

 140, 156, 172 



Transpiration, 10 



Trefoil, birds-foot {Lotus corniculatus), 35 



Trend, directional, 155 



Trichachne californica (Cottontop), 106 



Trifolium (Clovers) 

 pratense (red C), 85; pratense (Ken- 

 land red C), 32; repens (white 

 C), 35, 85, 98; repens (Ladino 

 white C), 30, 32, 35 



Trillium (Trilliums) 



erectum (purple T), 83; grandiflorum 

 (snow T), 83; undulatum (painted 

 T), 80 



Trisetum spicatum (Spike trisetum), 17 



Tropical rain forest, 82, 128, 155 



Tsuga canadensis (Hemlock), 163 



Tundra, 30, 36,44, 117, 174 



Tlixen, R., 177 



7>/)/ia (Cattail), 21,97, 140 



Typhetum association (Cattail associa- 

 tion), 180 



Utah, 33, 39, 40, 46, 47, 85, 86, 88, 148 



Vaccinium (Blueberries, Whortleber- 

 ries), 84 

 canadense (Canada B.), 84; myrtillus 

 (European W.), 18, 62, 157; sco- 

 parium (grouse W.), 84; uliginosum 

 (bog B.), 30, 36, 87, 103, 139, 

 187; vitis-idaea (mountain cran- 

 berry), 30, 63 



Vaseygrass (Paspalum urvillei), 52 



Vegetation, complexity, 140, 171, 185 

 dynamics, 184 

 form, 77, 92 

 snow-field, 157 



Vernal aspect, 87 



Viability of seeds, 41 



Vigor, 11, 20, 27, 51-52, 77, 90-92, 

 105. See also Vitality 



Viola (Violets), 83 



canadensis (Canada V), 80; palmata 

 (palm v.), 80; pedatifida (cutleaf 

 v.), 80, 128; sagiltata (arrowleaf 

 v.), 65 



Virginia, 50 



Virus, curly top, 51 



Vitality, 72, 90-92, 126, 173. See also 

 Vigor 



Vittadima community, 36 



Vivipary, 41 



Volume, 111-112 



Ukraine, 67 



Ulex europaeus (Common gorse), 72 



Umbelicariaceaea, 158 



Under-dispersed individuals, 1 1 3 



Uniformity in vegetation, 114, 150 



Umola pamculata (Sea oats), 19 



Union, 73, 84 



United States, 130, 184 



eastern, 51, 80 



Northwest, 51 



southeastern, 28 



southern, 92 



southwestern, 32, 46, 68 



western, 30, 51, 85 

 Ustilago (Smuts) 



marginatus (head S.), 93; striiformis 

 (stripe S.), 51 



Washington, 25, 31, 62, 73 

 Washington palm ( Washintoniafilifera), 



57 

 Water-table, 17 

 Watt, A. S., 143, 157 

 Weed, communities in Europe, 180 



groupings, 64 

 Weight of plants, 108, 118 



and volume, 1 1 1 

 Westnngia ngida, 36 

 Wheatgrass. See Agropyron 

 Whittaker, R. H., 160 

 Wilting percentage, 27 

 Wind, 38, 161 



Winter fat. See Eurotia lanata 

 Woodland, 68, 180 

 Working depth of root system, 107 



Index • 217 



