Mesophyte, 95 



Mesquite (Prosopsis), 29, 46, 68, 129 



Metcalfe, G., 141 



Meteorological data, 147 



Michigan, 13 



Microcommunity, 146 



Microhabitat, 41, 112, 125 



Microrelief, 141 



Microstand, 174 



Microtopography, 118 



Mineral nutrients, 1 1 



Minimal area, 124 



Minnesota, 28, 94, 150 



Minuartia stricta (Rock sandwort), 40, 

 57 



Miocene Epoch, 56 



Mississippi, 21 



Missouri, 85, 114 



Mobility of seeds, 41 



Montana, 40, 48, 53, 72, 107 



Mor humus, 80 



Mosaic, habitats and climax commu- 

 nities, 161 



Muhlenbergia (Muhlys) 



cuspidata (plains M.), 99; montana 

 (mountain M.), 47, 102, 108, 184 



Muhly. See Muhlenbergia 



Mull humus, 80 



Munroa squarrosa (False buffalograss), 

 49 



Mustards, 47, 51 



Mutualism, 53 



Mycorrhiza, ectotrophic, 53 

 endotrophic, 53 



Myrica cerifera (Wax myrtle), 20 



Natural areas, 175 

 Natural selection, 2, 15, 24 

 Nebraska, 21, 34, 38, 42, 68, 98, 107, 



140 

 Needle-and-thread. See Stipa 

 Negev, 40 



Nettle {Urtica dioica), 37 

 Nevada, 107 

 New Jersey, 67, 81 

 New Mexico, 61 

 New York, 82, 91 

 Niche, ecological, 54 

 Nicholson, A. J., 15 



Nicotiana (Tobacco), 39 



Nitrogen-fixation, 53 



Normal distribution, 113 



North America, 105, 130, 159, 187 



North Carolina, 20, 153 



North Dakota, 13, 23, 49, 70, 82, 84, 



99, 101, 115, 116, 128 

 Norway, 17, 18-19, 30, 36, 41, 62, 



157, 161, 178 

 Nymphaea (Water lily), 1 1 



Oak. See Quercus 



Oak-hickory forest, 181 



Oak-mountain mahogany zone, 187 



Oak wilt. See Endoconidiophora faga- 

 cearum 



Oceanicity, 181-182 



Oklahoma, 14,65, 78 



Opuntia (Prickly pear cactus), 11, 35, 

 53, 68, 93, 96, 98 

 fragilis, 144 



Orchardgrass. See Dadylis 



Orchids. See Orchidaceae 



Orchidaceae (Orchid family), 36, 53 



Order, use in classification of commu- 

 nities, 178, 179, 180 



Oregon, 51, 149 



Organism, complex, 62 



OrthocauHs floerkei, 18 



Ostrya virgimana (American hornbeam), 

 83 



Over-dispersed individuals, 113 



Oxalis stricta (Common yellow oxalis), 

 85 



Oxyria digyna (Mountain sorrel), 16 



Palatability of plants, 45, 110, 114 

 Panicum virgatum (Switchgrass), 38, 42 

 Papaver dahlianum (Poppy), 34 

 Parasitism, 51-53, 62 

 Parthenium argentatum (Feverfew), 37 

 Paspalum conjugatum (Paspalum), 112 

 Pathogen, 51 



Pattern, vegetational, 123, 131, 156- 

 157, 160 



and climax, 160, 164-165 



and frequency, 131-132 



causes of, 131-132 



definition, 131 



212 • Index 



