TABLE OF CONTENTS 
Page 
Pr.eface _ 5 
Introduction _ 7 
Botanical Collections _ 7 
Vegetational Studies_ 9 
Vegetation Map_ __ facing 14 
Flora _ 15 
Vegetation Areas _ 16 
Chihuahuan Desert _ 16 
1. Creosote-yucca-mesquite _ 17 
2. Mesquite-grassland _ 18 
3. Succulent desert_20 
Sierra Madre Occidental _ 20 
1. Oak-agave-juniper _'_ 21 
2. Pine forest _ 22 
Sonoran Desert _ 22 
1. Colorado River Delta _ 22 
2. Creosote-palo verde-cacti _ 23 
% 
3. Sonoran mesquite-grasslands _ 24 
4. Subtropical mimosaceae-cacti _ 24 
Sinaloa Tropical _ 25 
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