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TEXTBOOK OF BOTANY 



the air at low tide. Waves, especially during storms, rupture the blades 

 of the larger plants, and it is often difficult to find a perfect specimen. 



The simplest brown algae structurally are filamentous and super- 

 ficially resemble some of the greens. The majority, however, are large 



Fig. 288. PustelsUi, a brown alga, on the rocky coast ot Santa Cruz County, 

 Cahfornia. The plants are covered by water at high tide. Below, near the water, 

 are other brown algae. Photo by W. S. Cooper. 



and parenchymatous with a rather high degree of differentiation in the 

 plant body ( Fig. 288 ) . The leathery kelps, abundant in the colder tem- 

 perate waters, have internal tissues that resemble the sieve tubes of seed 

 plants. These algae consist of branching root-like holdfasts attached to 

 rocks or other substrates, a long submerged stalk, and one or more con- 

 spicuously large, ribbon-like, or variously shaped floating blades. Some 



