THE TWO GREAT CLASSES OF PLANTS 183 



353. It happens that the spores of seed-bearing plants 

 are borne amongst a mass of specially developed leaves 

 known as flowers: therefore, these plants have been known 

 as the flowering plants. Some of the leaves are developed as 

 envelopes (calyx, corolla), and others as spore-bearing 

 parts, or sporophylls (stamens, pistils). But the spores of 

 the lower plants, as of ferns and mosses, may also be borne 

 in specially developed foliage, so that the line of demar- 

 cation between flowering plants and flowerless plants is not 

 so definite as was once supposed. The one definite dis- 

 tinction between these two classes of plants is the fact that 

 one class produces seeds and the other does not. The seed- 

 plants are now often called spermaphytes, but there is no 

 single coordinate term to set off those which do not bear 

 seeds. It is quite as well, for popular purposes, to use the old 

 terms, phenogams for the seed-bearing plants and cryptogams 

 for the others. These terms have been objected to in recent 

 years because their etymology does not express literal facts 

 (phenogam refers to the fact that the flowers are showy, and 

 cryptogam to the fact that the parts are hidden), but the 

 terms represent distinct ideas in classification. Nearly 

 every word in the language has grown away from its ety- 

 mology. The cryptogams include three great series of 

 plants — the Thallophytes or algae, lichens and fungi; the 

 Bryophytes or moss-like plants; the Pteridophytes or fern- 

 like plants. In each of these series there are many families. 

 See the following Chapter. 



Review. — What is a spore? Describe the appearance of some 

 fern plant that you have studied. What are the spores and sporangia? 

 What is a sorus? Indusium? What grows from the spore? How does 

 the new "fern" plant arise? What is meant by the ph ase "alternation 

 of generations?" Define gametophyte and sporophyte. Describe 

 the alternation in flowering plants. Explain the flower from this point 

 of view. What is the significance of the word spermaphyte? Contrast 

 phenogam and cryptogam. 



Note. — All the details of fertilization and of the development of 



