ELEMENTS OF BOTANY. XV11 



106. The preceding considerations refer solely to rhamogamous Plants, or 

 those which bear flowers, consisting of stamens and pistils, and produce seeds, 

 which contain an embryo, or a rudiment of a future plant. 



107. But there are plants of a lower grade, which do not bear flowers furnished 

 with ordinary stamens and pistils, nor seeds containing an embryo, but in place 

 of seeds they produce minute powdery bodies, called Spores. These are termed 



11. Cryptogamons or Flowerless Plants. 



108. The stems of the higher orders of Cryptogamous Plants — and these only 

 arc embraced in this work — exhibit nearly the same anatomical structure as 

 those of Phamogamous Plants. But they grow only from the apex, without any 

 perceptible increase of diameter, and therefore are termed Acrogens or Point- 

 growers. 



109. The different orders presenting no common type, the habit, the mode of 

 inflorescence, and the process of fertilization, so far as it is known, being different 

 in all of them, the characteristics of each are more conveniently explained in the 

 body of the work, and need not be enumerated here. 



12. Classification. 



110. Classification consists in the arranging of plants possessing like structure, 

 habits, &c., into groups, designating them by proper names, and defining them 

 by appropriate characters. 



111. An assemblage of individuals which are so essentially alike as to indicate 

 their descent from a common parent, and which preserve their characteristics 

 when propagated from seed, is termed a Species. But circumstances connected 

 with the growth of an individual may produce some deviation from its ordinary 

 state, and it then becomes a Variety. 



112. When the pistil of one species is fertilized by the pollen of another allied 

 species, the result is a Hybrid. 



113. An assemblage of species agreeing with one another in structure and ap- 

 pearance constitutes a Genus. In the same manner, although with fewer points 

 of agreement, genera are collected into Orders, or Families, and these, in turn, into 

 Classes. 



114. But each of these may include members that agree in some important 

 points, which are not common to the others. Of such are formed the intermedi- 

 ate divisions of Subgenera, Suborders, and Subclasses. 



115. There are two modes or systems of classification; the Artificial System 

 of Linnaeus, and the Natural System of Jussieu. 



116. In the Artificial System, the Classes and Orders are founded on the num- 

 ber, position, and connection of the stamens and pistils, regardless of any other 

 relationship In the Natural System, every part of the plant is taken into consid- 

 eration ; and the Orders embrace those genera which agree with each other in the 

 greatest number of important particulars. The latter system is now in almost 

 universal use, and is the one adopted in this work. 



