DIFFERENT ALTITUDES IN COLORADO 39 
SYNOPSIS OF XEROPHYTIC GRASSLANDS IN NORTHERN 
CoLoRAbo! 
A. Associations of mixed character belonging to the plains 
region; not clearly dominated by grasses or sedges: 
1. Gutierrezia-Artemisia Association. 
2. Plains Ruderal Association. 
3. Chrysothamnus Association. 
4. Artemisia ‘filifolia Consociation (of the Sand Hills Mixed 
Association). 
B. Associations dominated by sedges; mountain communities 
not represented on the plains (Ramaley, 11): 
5. Carex stenophylla Grassland Association ; foothills and montane. 
6. Carex Rossii Grassland Association; montane and subalpine. 
7. Carex siccata Grassland Association; montane and subalpine. 
8. Carex elynoides Grassland Association; subalpine and alpine. 
C. Associations of the Mixed Dry Grassland Type: 
9. Inceptive Dry Grassland Association of the Foothill Zone 
(the Foothills Primitive Grassland of Vestal, 20). 
10. Derivative Dry Grassland Association of the Foothill Zone 
(the Foothills Mixed Grassland of Vestal, 20). 
11. Inceptive Dry Grassland Association of the Montane Zone. 
12. Derivative Dry Grassland Association of the Montane Zone. 
D. Associations dominated by one or a few species of grasses: 
13. Short Grass Association; plains and mountain front; domi- 
nated by Bouteloua and Bulbilis. 
14. Wheat Grass Association, mountain front chiefly; dominated 
by Agropyron Smith. 
. Andropogon Bunch Grass Association; plains and mountain 
front. 
16. Porcupine Grass Association; plains and foothills, occasionally 
montane; dominated by Stipa 
17. Sand Hills Mixed Association; plains; dominated by Cala- 
movilfa and Andropogon. 
1It is often wean to decide just what communities should be included as 
“grassland.” The writer omits lichen and mat associations, since they hove almost 
i 
on 


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these are best known as ‘“‘scrub.” The Prairie Grass Association (of Vestal) is not 
included, as it is mesophytic. 
