THE VARIETY OF PLANT LIFE 



91 



penetration. The 2000 species which constitute this phylum are 

 more delicate in appearance than the fleshy and massive Brown 

 Algae and many of them have exquisitely intricate and orna- 

 mental body forms (fig. 59). They are rarely seen except torn 

 loose from their holdfasts after a storm; when, washed up on the 

 beaches, they are only tattered remnants of their former graceful 

 selves. One papery and fragile genus (Porphyra), purplish in color, 

 is cooked and eaten in the British Isles where it is known as laver. 

 Dulse is another genus {Rhodymenia) also used as food in Great 



A C D 



Fig. 60. — Red algae of economic importance include dulse (A), Porphyra (B), 

 the agar seaweed (C), and Irish moss (D). 



Britain. Irish Moss (Chondrus) is one of the few seaweeds collected 

 along the Atlantic coast of the United States for commercial 

 purposes; being made into a gelatinous product for curing leather 

 and sizing cloth. Commercial agar, or vegetable gelatine, is made 

 from a red alga known as Gelidium (fig. 60). 



Over 20,000 species of thallus plants lack chlorophyll and 

 hence must live as saprophytes or parasites; these are grouped 

 into the phylum Mycophyta, popularly known as the Fungi. 

 The phylum is subdivided into classes on the basis of the type of 

 reproductive structures developed during sexual and asexual 

 reproduction. One group, the Algae-like Fungi, has a simple 

 vegetative body resembling the filamentous algae; among them 



