CLASSES OF PLANTS 73 



ered; e. g., ferns, mosses, sea-weeds, toadstools, molds, etc. 

 These are all grouped together under the name of Cryptogams, 

 but it is not thereby meant to indicate that there is a close 

 relationship between the various members of the group. It 

 signifies only that the members of which it is composed do not 

 bear seed. As a whole the Spermatophytes are much more 

 complex and for certain reasons are regarded as of a higher order 

 than the Cryptogams. 



175. Of the Cryptogams, the highest class — those most 

 nearly resembling the Spermatophytes — are the Pteridophytes, 

 including the ferns and their allies. Most of these have an 

 underground stem (rootstock or rhizome) with a system of true 

 roots and a series of leaves held aloft on long petioles or stipes. 

 The microscopic structure of the organs, too, resembles in a 

 general way that of similar organs in the higher plants. The 

 common ferns, the scouring-rushes and the club-mosses are 

 familiar examples of this group. 



176. Next in order below the Pteridophytes come the Bryo- 

 phytes, to which group belong the mosses and liverworts. 

 These plants are all small. The moss plant consists of a slender 

 stem, with scale-like leaves, but no true roots, and there are no 

 well-developed vascular bundles in the stem. In liverworts 

 there is usually no distinction of stem and leaf. The body of 

 the plant consists simply of a flat expanse of green tissue. In 

 place of roots the mosses and liverworts have organs which 

 resemble root hairs and are called rhizoids. 



177. All plants not included in the foregoing groups are 

 classed together as Thallophytes — a large and heterogeneous 

 group which comprises all the lowxr or simpler plants. The 

 body of a' Thallophyte is never differentiated into root, stem 

 and leaves, as is usually the case in the higher groups, and there 

 are more exact distinctions to be observed in the methods of 

 reproduction. The Thallophytes are divisil)le into two very 

 distinct groups, algas and fungi, which are distinguished by the 



