1^2 PLANT STRUCTURES 



serve to distinguish the four great groups of plants. It 

 must not be supposed that these are the only characters, 

 or even the most important ones in every case, but they 

 are convenient for our purpose. Two characters are given 

 for each of the first three groups — one a positive character 

 which belongs to it, the other a negative character which 

 distinguishes it from the group above, and becomes the 

 positive character of that group. 



(1) ThaUopJiytes. — Thallus body, but no archegonia. 



(2) Bryojiliytes. — Archegonia, but no vascular system. 



(3) Pteridophytes. — Vascular system, but no seeds. 



(4) Spermatophytes. — Seeds. 



93. General characters of Spermatophytes. — This is the 

 greatest group of plants in rank and in display. So con- 

 spicuous are they, and so much do they enter into our 

 experience, that they have often been studied as "botany," 

 to the exclusion of the other groups. The lower groups 

 are not meiely necessary to fill out any general view of the 

 plant kingdom, but they are absolutely essential to an 

 understanding of the structures of the highest group. 



This great dominant group has received a variety of 

 names. Sometimes they are called Anthophytes, meaning 

 "Flowering plants," with the idea that they are distin- 

 guished by the production of "flowers." A flower is difii- 

 cult to define, but in the popular sense all Spermatophytes 

 do not produce flowers, while in another sense the strobilus 

 of Pteridophytes is a flower. Hence the flower does not 

 accurately limit the group, and the name Anthophytes is 

 not in general use. Much more commonly the group is 

 called Phanerogams (sometimes corrupted into Phaenogams 

 or even Phenogams), meaning "evident sexual reproduc- 

 tion." At the time this name was proposed all the other 

 groups were called Cryptogams, meaning "hidden sexual 

 reproduction." It is a curious fact that the names ought 

 to have been reversed, for sexual reproduction is much more 

 evident in Cryptogams than in Phanerogams, the mistake 



