136 



OUTLINE OF PLANT GEOGRAPHY 



reefs, exposed to the tremendous Pacific surf, are usually tough 

 and leathery in texture, fitted to withstand the buffeting of the 

 heavy waves. Some of these large red species, like the spiny 

 Cigartina and Iridea, the latter reflecting peacock-hues in the 

 shallow pools, are very conspicuous. 



The most striking marine plants of this coast, however, are the 

 big brown sea-weeds, or kelps, which reach extraordinary size, 



and show great diversity of 



form. Some of them, like 

 Fucus, are entirely exposed at 

 low tide, and drape the rocks 

 as they do on the northern At- 

 lantic coast; others are rooted 

 in water far below tide mark, 

 and their leaf-like fronds float 

 near the surface, often buoyed 

 up by air-bladders. The tough 

 stems are anchored by strong 

 root-like hold-fasts in water 

 many fathoms deep. 



Of these giant kelps, the 

 great bladder-kelp (Microcys- 

 tis) is abundant from Alaska 

 to Santa Barbara, and great 

 beds of this kelp, off shore, act 

 as a quite efficient breakwater. 

 Another very large species, 

 Nereocystis Lutkeana, some- 

 times attains a length of over 

 100 feet. The big leaves are 

 attached to a single air-bladder 

 the size of a baseball, the stem tapering gradually to the slender 

 solid stem. This huge plant is the growth of a single season. 

 Much like Nereocystis is the " bull-kelp" (Pelagophycus) of 

 southern California, in which the float is the size of a coconut, 

 and the big leaves are attached to two great antler-like branches. 

 Another kelp peculiar to the Pacific coast is the sea-palm (Pos- 

 telsia palmaeformis) , a stout upright plant about two feet high 

 growing on rocks exposed to the full force of the breakers. It 



I 



Fig. 36. — Sea-palms (Postelsia palmaefor 

 mis). Photo., Miss E. M. Bartlett. 



