HOW TO KNOW THE SEAWEEDS 



100a Vesicles produced by inflation of portions of flat, dichotomous 

 blades. Fig. 135 Fucus vesiculosus 



Fig. 135. Fucus vesiculosus Lin- 

 naeus 



An upper part of a plant to 

 show the dichotomous branching 

 and the vesicles which are usu- 

 ally paired, X 0.56. This is one 

 of the commonest of all the ma- 

 rine algae along the Atlantic 

 Coast from North Carolina north- 

 ward. Fucus evanescens C. Agardh 

 is a north Pacific coast species 

 having vesicles, but other mem- 

 bers of this common genus lack 

 vesicles and are treated elsewhere 

 in this key (See step 135). 



Figure 135 



100b Vesicles not produced in flat, dichotomous blades 



101 



101a Vesicles borne on either side of flat, ligulate, percurrent axes. 

 Fig. 136 Egregia 



Fig. 136. Egregia laevigata Setchell 



A. Habit of an entire plant, X 0.04. B. A small portion of one 

 of the flat axes bearing lateral blades many of which have vesicles at 

 their bases, X 0.5. This is one of the large brown algae of central 

 and southern California which attracts the most attention because of 

 its pecuHar form and its abundance along some bathing beaches. 

 It has been called the "Feather Boa." Another species, E. menziesii 

 (Turner) Areschoug, is similar in habit but occurs from central Cali- 

 fornia northward to Canada. 



104 



