36 THE BKOAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 



enormous woody masses which frequently form the bases of the 

 Arctostaphylos and Adenostoma clumps are very prominent here, 

 occupying a surprising amount of the ground area. The quadrat 

 shown in figure 3 gives the following summary: 



Clumps. Sleme. 



Adenostoma 7 23 



Arctostaphylos 18 44 



Quercus durata 4 8 



Heteromeles 3 11 



Total 32 86 



An occasional plant of Diplacus glutinosus, a half-shrub, is found 

 here, badly off for light. Depauperate specimens of Symphoricarpos 

 racemosus are rather frequent. Herbaceous growth occurs, but not 

 in great amount. The most abundant is Aster radulinus, which 

 produces nothing but basal leaves under the solid chaparral cover. 

 The only other is the fern Gymnogramme triangularis. The woody 

 bases of the shrubs are covered with mosses and small Cladonias. 

 Humus is in fair amount and litter is abundant. Where the trail 

 crosses the ravine bottom a single young specimen of Quercus agri- 

 folia suggests a tendency toward mesophytic forest conditions. 



Station 4. 



Crossing the ravine, the vegetation is seen to change, with no 

 transition zone, to Adenostoma dominance. The striking contrast 

 is manifestly related to the sharply angular change of slope at the 

 ravine bottom. Station 4 is exactly opposite station 3 and at an 

 equal height. The bushes, averaging 1.2 to 1.5 meters, are decidedly 

 better in appearance than those of stations 1 and 2, and the ground 

 is controlled by them to a much greater degree, though not completely. 

 The quadrat (fig. 4) contains the following: 



Clumps. Stems. 



Adenostoma 24 133 



Arctostaphylos 6 42 



Quercus durata 3 4 



Total 32 179 



The undergrowth is exceedingly sparse, including a few individuals 

 of Aster radulinus and Gymnogramme triangularis. Humus is 

 scanty, but there is considerable litter beneath the shrubs. A plant 

 of Quercus wislizeni close to the quadrat has three trunks 2.5 meters 

 high, standing well above everything else. 



Station 6. 



Going northward up the gentle slope, we pass through vegetation 

 like that of station 4, but becoming lower and less dense. There 

 are frequent areas where one may walk between the bushes, many of 

 which are of low stature. Adenostoma is everywhere dominant, 

 and Arctostaphylos, Heteromeles, Quercus durata, and Q. wislizeni are 

 also present. Undergrowth is practically absent, and humus and 

 litter are scanty. 



