FLOWERLESS PLANTS 151 



Phanerogams and Cryptogams. — In the widest sense the plant 

 world is divided into two great groups, the flowering plants, or 

 Phanerogams, and the flowerless plants, or Cryptogams. This is 

 an old system of classification, but it shows one very important 

 distinction in the plant kingdom. 



The flowerless plants are much simpler in structure than the 

 flowering plants. We are apt to entirely overlook them in a 

 casual glance at vegetation in a landscape. Thousands of species 

 exist so small that we cannot see them with the unaided eye. 

 Many kinds hide themselves in the water, while still others may 

 lie flat on the ground or cling to the bark of trees and thus escape 

 observation. Yet one of the cryptogams is over a thousand feet 

 in length, one of the longest plants in the world. 



Classification of the Plant Kingdom. — The entire plant king- 

 dom has been grouped as follows by the later botanists : — 



^ ci ^ 7 ^ \ Angiosperrns , true flowering plants. 



1. Spermatopm/tes. ] ^ .. . , .i . i,. 



( (jrymno sperms, the pmes and their allies. 



2. Ptendophytes. The fern plants and their allies. 



3. Bryophytes. Moss plants and their allies. 



4. Thallophyt^s. Plants in which the plant body is a thallus, 

 that is, the body is not divided into root, stem, and leaves. A 

 seaweed and a mushroom are good examples. The Thallophytes 

 form two groups : the Algae and the Fungi. 



The extent of the plant kingdom can only be hinted at, because each day 

 new species are added to the lists. There are about 110,000 species of flower- 

 ing plants and perhaps half as many flowerless plants. The latter consist of 

 nearly 3500 species of fernlike plants, some 16,500 species of mosses, over 

 5600 lichens (plants consisting of a partnership between algse and fungi), 

 approximately 55,000 species of fungi, and 16,000 species of algse. 



Sexual Reproduction in Flowering Plants. — Flowering plants re- 

 produce their kind by the formation of seeds. As we know, the 

 flower produces in the ovary structures which are known as 

 ovules. In the interior of the ovule is found a clear protoplasmic 

 area which is called the embryo sac. In this area is a cell (the 

 egg cell) which is destined to form the future plant. In the pollen 

 grain is found another cell, the sperm. This cell, after the ger- 



