. _ FUCACEiE. 43 



This is not a common plant. It resembles F. vesicu- 

 losa, but may be readily distinguished bj^ »J£s narrow 

 side-branches, its thinner texture, and the smaller quan- 

 tity of saline matter winch it contains t This latter pe- 

 culiarity causes it to require less soaking, and to dry 

 more quickly than other species of the genus; 



Fucus serratus. Serrated Wrack. 



Frond flat, forked, toothed at the edge* haying a strong 

 midrib, from two to four feet long, or -more. Air-vessels, 

 none. - Spore-receptacles flat, at/the ends of the branches. 



This species is very common, and is easily identified. 

 The width of the frond and the depth of its serratures 

 vary considerably; but the general character of the 

 plant is never lost. J ..?-■- 



Fucus nodosns. Knotted Wrack^ or Sea- 

 whistles, s * X • 



Frond flattened, without a distinct midrib, one to five 

 feet long, a quarter of an inch to an inch wide ; branches 

 springing from slight projections, small at the base, and 

 more or less pointed at. the apex. Air-vessels very large, 

 oval, formed in the main stem and branches. Spore-recep- 

 tacles egg-shaped, on erect sjender stalks, springing from 

 projections on the branches^ bright yellow when ripe. 



This is the largest, toughest, and most rigid British Fa- 

 cus. It grows nearer to low- Water mark than any other 

 species of the genus, and is usually more or less covered 

 with Polysiphoniti fastigiatd. It may be easily recog- 

 nized by its thick narrow frond and large air-vessels. 



