i6o 



BOTANICAL GAZETTE 



[SEPTEMBER 



TABLE I 



Topographic areas (habitats) and associated vegetation-types 

 in granitic foothills complex 



TOPOGRAPHIC AREAS 



The geographic mean is that pre- 

 sented by rather exposed and xero- 

 phytic sloping surfaces, thinly covered 

 with rock-waste of mixed texture, 

 rather gravelly and with surface 

 rocks. Local departures from the 

 general condition are as follows: 



i. Exposed rock surfaces (bowlders 

 and rock-walls) 



2. Rock-crevices 



3. Rock-strewn detritus slopes 



4. Rock-talus 



5. Compacted granite-gravel floors 

 and side-slopes 



6. Loose granite-gravel floors, 

 washes, and talus (gravel-slides) 



7. Mixed-soil floors and detritus- 

 slopes (fine soil with imbedded and 

 superficial rock-fragments of various 

 sizes) 



8. Fine-soil floors and detritus- 

 slopes (infrequent) 



9. Less xerophytic side-slopes 

 (mostly north-facing, mostly of con- 

 siderable gradient, and best developed 

 in valleys) 



10. Narrow mesophytic ravines 

 (best developed as small side-canyons, 

 especially on the south side of east- 

 ward flowing main streams) 



11. Stream-sides in shaded ravines 



12. Stream-sides 

 bottoms 



in open canyon 



VEGETATION-TYPES 



The general ground-cover is mixed 

 foothills grassland and primitive 

 grassland, largely of grasses and herbs 

 of the plains, with admixture of Rocky 

 Mountain herbs, not all xerophytic. 

 Scattered rock pines and plants of 

 the mixed shrub association, singly 

 or in clumps, dot the surface. In 

 special habitats occur: 



1. Xerophytic lichen association 



2. Selaginella, shrubs of Jamesia 

 and Ribes, rock pine 



3. Mixed grassland, and mixed 

 consocies of primitive grassland, with 

 higher proportion of woody plants 

 (rock pines, mixed shrub, Ccanothus, 

 Arctostaphylos) 



4. Artemisia frigida-Koeleria con- 

 socies of primitive grassland (18) 



5. Compacted granite-gravel con- 

 socies of primitive grassland (18) with 

 rosette plants; Arctostaphylos 



6. Primitive grassland, with 

 Geranium-C/irysopsis consocies, mat 

 (rosette) consocies of gravel-slides, etc. 



7. Foothills mixed grassland, with 

 addition of other components, Ceano- 

 thus, sumac, pine, etc. 



8. Foothills mixed grassland, of a 

 form approaching plains short-grass 



9. Mixture of mixed shrub, rather 

 less xerophytic mixed grassland, and 

 pine associations, with representatives 

 of canyon forest and scattered trees of 

 Pscudotsuga 



10. Mesophytic representations of 

 mixed shrub, Pscudotsuga, aspen, 

 Symphoricarpos, canyon forest,, and 

 mesophytic grassland associations. 

 Mosses, Saxifraga, etc., in wet rock- 

 crevices 



11. Bctula, Alnus, Corylus, and 

 Acer glabrum of the canyon forest; 

 shrubs; moist -soil herbs, as Herac- 

 leum, Rumex, etc. 



12. Populus anguslijolia, willows, 

 etc. 



