200 



THE PLANT WORLD 



Self-Testing Exercise 



Molds grow under favorable conditions of (1), (2), 



(3), and (4) heat. They spoil many (5) and 



cause (6). Some molds give (7) to cheese. Molds 



may be kept out of food by keeping the food (8) and well 



(9). Molds send out rootlike threads, (10), which give 



off (11) (12) and absorb (13). 



PROBLEM VH. WHAT ARE SOME EXAMPLES OF COMMON 



ALGAE? 



The Fungi which include all the plants which we have so far 

 studied in this unit constitute one large division of thallophytes. 

 We now come to the other main group, the algae. In the classifi- 

 cation given below we find three classes of algae. 



The Algae. The algae are nearly all water plants, although some 

 few species may be found on tree trunks and rocks which are exposed 

 to moisture. They are a large group of chlorophyll-bearing plants, 

 although in some forms the characteristic green color of chlorophyll 

 is masked by some other coloring matter, usually red and brown. 

 They have many forms, ranging from single cells to filamentous 

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

 as in some seaweeds. Our attention is called to them in an un- 



Chlorophyceae 



\ / 



.T&aeophy< 



brown / c 



'ceae 



brown J g\£o& 



THALLOPMYTA 



^PWoomycetes-/ Eumycetes \_Phodophyceae 



Jnucor 



yeasts -mushrooms 



red ctigae 



I. The Green algae are of countless forms, unicellular, filamentous, plate-like, and in irregular 

 masses of cells. There are both fresh-water and salt-water forms, and others live on land. The 

 so-called " Red-Snow" is a form living in snow patches. Pleurococcus and vaucheria are also 

 examples. Some 5000 species have been described. 



II. The Brown algae are nearly all marine plants. We know them as seaweeds. About 

 1000 species are known. 



III. The Red algae, mostly marine, are our most delicate and beautiful seaweeds. There are 

 about 3000 named species. 



IV. The Fungi are without chlorophyll. There are about 75,000 species in all. Many of 

 them are harmful. There are two classes: Phy corny cetes, the molds - , and Eumycetes, yeaats, 

 mushrooms, and puffballs. Bacteria are usually classed as Fungi. 



