344 IOWA ACADEMY OF SCIENCE Vol. XXVI, 1919 



Pinus contort a is much less common than Picca sitchcnsis. Where 

 it is most exposed it has a very short trunk with long, depressed 

 branches. The whole tree is greatly distorted and usually not more 

 than two or three meters in height. 



Vacci)iiii}ii ovatitiii is the most abundant and characteristic shrub 

 of this area. It forms low, cushion-like clumps of remarkably uni- 

 form shape. These cushions have a low pitch on the seaward side, 

 but a more abrupt slope on the landward, so that when one is looking 

 across them from the west he sees a series of smooth, low, and 

 gently sloping mounds, but from the east they present the appearance 

 of large green hummocks. The branches are so closely matted and 

 interwoven that one can often sit on the top of a bush without bend- 

 ing it over. 



Myrica calif oniica forms clumps somewhat similar to those of 

 Vacciniuni ovatuin. Gaidthcria sJiallon is dwarfed and matted, mak- 

 ing a continuous turf-like growth where it is fully exposed. Ledum 

 columhianum, Rhododendron calif orniciim, Rosa nutkana and Ruhiis 

 spectahilis are much dwarfed. The same is true of Arctostaphylos 

 tomentosa, which, however, grows- very sparingly in the most ex- 

 posed places. Vacciniuni uliginosum var. mncronatmn is abundant 

 m some localities, but it is too low to be afifected by the winds. 



Of the herbaceous plants it may be said in general that they show 

 the effects of the peculiar environment just in proportion to the 

 height which they reach under normal conditions ; that is, they show 

 more or less tendency to become low and stout. 



The association we have just been considering passes more or less 

 gradually into the forest on the landward side. The low vegetation 

 that is fully exposed to the winds from the sea protects that on its 

 leeward side, thus enabling the latter to grow a little taller, and this 

 in turn protects that which succeeds. In this manner the powerful 

 air currents that could not be withstood by the taller trees if they 

 were exposed from the ground upward, are shot over their tops by 

 the inclined plane up which they have been directed. 



In some places the forest is extremely dense, in others it is more 

 open. The area studied includes only the narrow strip of com- 

 paratively low coastal forest, which is approximately co-extensive 

 with the distribution of Pimis conforfa in this section. The land oc- 

 cupied by this forest association is in places comparatively level, and 

 here we find the closest stand of trees. In other places it is hilly or 

 cut by ravines and small swampy tracts. The species making up 

 this assemblage are in the majority of cases the same as those occur- 



