CLASSIFICATION OF PLANTS 519 



Class III Sac fungi. Produce spores in a sac. Examples 

 are the yeasts, powdery mildews, and many others. 



Class IV Club fungi are so-called because their spores are 

 produced upon a club-shaped structure. Mushrooms, puffballs, 

 smuts, and rusts belong to this group. 



The subphylum Algae includes the chlorophyll-bearing thallo- 

 phytes. In some forms the chlorophyll is masked by some other 

 coloring matter. They range from single-celled forms to filamen- 

 tous colonies or even long ribbon or rope-like masses many feet in 

 length. They are nearly all aquatic. The subphylum Algae is 

 subdivided as follows : 



Class I Blue-green algae contain a blue pigment in the 

 cells in addition to the green color. Examples are Nostoc pru- 

 niforme and Oscillatori wolacea. 



Class II Green algae are of countless forms, unicellular, 

 filamentous, platelike, and in irregular masses of cells. There 

 are both fresh-water and salt-water forms, and others live on 

 land. One form will grow on snow patches. Pleurococcus vul- 

 garis and Vaucheria terrestris are examples. 



Class III Brown algae are nearly all marine plants. 

 They are the commonly known seaweeds. 



Class IV Red algae are mostly marine. Our most deli- 

 cate and beautiful seaweeds belong to this main class. 



II. Phylum BRYOPHYTA (Gr., bryon moss; phyton- 

 plant) . Contains only two classes, the liverworts and the mosses. 

 These plants are small and live mostly on land. They show a 

 greater development of tissues than the algae and may be 

 either thallus-like (liverworts) or have stems with rootlike pro- 

 jections and very simple leaves. They reproduce by forming 

 spores. 



III. Phylum PTERIDOPHYTA (Gr., pteris fern). This 

 includes a group which, when the world was younger, played a 

 very important part in the vegetation on the earth. Most coal is 



