CHAPTER XVII 
LIFE HISTORIES OF ALG^E 
206. The Main Groups of Algae. The plants that rank 
next in the scale of life below the liverworts are the Algae. 
On the basis of color they fall naturally into four main 
groups or phyla, as follows: 
1. Blue-green algae (Cyanophycese) 
2. Green algae (Chlorophyceae) 
3. Brown algae (Phaeophyceae) 
4. Red algae (Rhodophyceae) . 
Associated with these differences in color are certain dif- 
ferences of structure, which also lead to a similar grouping. 
In recent years the above four groups have been further 
subdivided into seven phyla, on the basis of other char- 
acters than color. A study of one of the commoner brown 
algae, Ascophyllum, will serve to illustrate many funda- 
mental facts about the algae in general. 
ASCOPHYLLUM 
207. Habitat of Ascophyllum. This plant, and the 
closely related Fucus, have become familiar in inland 
markets, because they are commonly used as a packing in 
the shipment of crabs and other kinds of "shell fish." 
Ascophyllum and Fucus, and their near relatives, consti- 
tute the family Fucacea. For the most part they are 
inhabitants of the ocean, or of brackish water, or, in rare 
cases, of fresh water. The two genera mentioned are 
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