PROBLEM / What Kinds of Plants Inhabit the Earth? 



The two large groups of plants. In de- 

 scribing animals it was convenient to 

 speak of animals with a backbone and 

 animals without a backbone. Later we 

 sorted those without a backbone into 

 different phyla. In describing plants we 

 again very simply speak of two kinds, 

 those with flowers and seeds and those 

 without. People sometimes carelessly use 

 the words flower and plant as though 

 they mean the same thing. The flower, or 

 blossom, is only part of a plant, just as 

 the eye or the heart is only part of an 

 animal. Some plants bear flowers at cer- 

 tain times in the life of the plant. Others 

 never bear flowers. The plants that never 

 bear flowers are not the trees and the 



grasses which you may be thinking of. 

 Trees and grasses have flowers although 

 they are often so tiny or so unlike ordi- 

 nary flowers that they may escape your 

 notice. Trees and grasses are therefore 

 flowering plants, together with roses and 

 violets and daisies and many others. 



The true "plants without flowers" bear 

 no flowers of any kind nor do they form 

 seeds; and besides, as you will see, most 

 of them differ from the flowering plants 

 in their general make-up. Some differ so 

 widely that you might not recognize 

 them as plants at all. You will study the 

 plants without flowers first. There are 

 three divisions or phyla of flowerless 

 plants. 



THALLOPHYTES 



Agaricus 



BRYOPHYTES 



Pigeon-wheat moss 



Fic. 95 Examples of the four large groups in the plant kingdom. Which of these groups 



