INDEX TO GENERA. 



Abronia 1 68 



Acer 91 



Achillea. 137 



Acerates 150 



Aconitum 79 



Actaea. 79 



^Ecidium 202 



Agrimonia 105 



Agropyrum 196 



Agrostemma 86 



Agrostis 191 



Alisma 185 



Allium 183 



Allocarya 156 



Alnus 178 



Alopecuriis 191 



Amarantus. 169 



Ambrosia 132 



Amelanchier 106 



Amorpha 94 



Ampelopsis 91 



Anaphalis 131 



Andropogon 189 



Androsace 149 



Anemone 75 



Angelica 117 



Antennaria 131 



Anthemis 137 



Aphyllon 165 



Aplopappus 121 



Apocynum 150 



Aquilegia 78 



Arabis 81 , 204 



Aralia . . . II7 



Arceuthobium 1 76 



Arctostaphylos 147 



Arenaria 87 



Argemone 80 



Aristida 1 90 



Arnica 139 



Artemisia 137 



Asclepias 150 



Asplenium 199 



Aster 125 



Astragalus 95, 205 



Atriplex 171 



— 16 



Aulacomnium 200 



Bahia 135 



Balsamorhiza 133 



Barbarea 80 



Batrachospernium 202 



Barbula 200 



Beckmannia 193 



Berberis 80 



Betula 178 



Bidens 134 



Bigelovia 122 



Bouteloua 193 



Brachythecium 201 



Brassica 83 



Brickellia 119 



Bromus 196 



Brunella 167 



Bryanthus 147 



Bryum 201 



Buchloe 1 93 



Bupleurum 115 



Cactus 114 



Calamagrostis 192 



Calandrinia 88 



Callitriche no 



Calochortus 183 



Caltha 78 



Calypso 181 



Campanula 147 



Capsella 84 



Cardamine 8i 



Carex 187 



Carum 116 



Castilleia 163 



Catabrosa 194 



Ceanothus 91 



Cenchrus 190 



Cerastium 86 



Ceratodon 200 



Cercocarpus xoi 



Cereus 115 



Chasnactis 134 



Chaniferhodos 105 



Chara 202 



Cheilanthes . 199 



Chenopodium 170 



