MESA AND FOOTHILL VEGETATION 



37 



accurately along with the topography so that the relation between their 

 distribution and the topography can be observed readily by the reader. 

 It is hoped that the maps will show at a glance what pages of descrip- 

 tion would not indicate. The physiography and soil conditions are 



Fig. i. — Thorn Apple. Crataegus spp. — The different species of Crataegus are 

 evenly distributed, being the most abundant shrubs or small trees of the gulches. With 

 choke cherries and thimble berries they form impassable growths in some places. Small 

 clumps are getting started in the ravines on the sides of the mesa. In the depressions 

 and amphitheaters on the east and south slopes a good start of Crataegus has been made 

 due to seepage water as explained in the text. Here it occurs along with skunk bush, 

 choke cherry and Indian currant. 



discussed in the paper by Mr. Dodds and should be kept in mind in 

 considering the distribution of any particular plant. 



The careful mapping of the vegetation of an area of limited extent 

 s valuable as throwing light upon plant distribution and the relation 



