72 The Natural System of Botany. 



THE NATURAL SYSTEM OF BOTANY. 



RVM BER THRXX. 



Exogenae or Dicotyledonous plants are next subdivided into 

 two very natural and easily ascertained families. All those 

 whose seed is enclosed in a pericarp, or seed vessel, are in- 

 cluded in the division AngjospermjE, signifying covered seeds, 

 and all whose seed is destitute of an outer covering, belon<* to 

 the division Gymnosperm^:, naked seeds. The first division of 

 Endogenae,or Monocotyledonous plants, consists of those which 

 have a true calyx and corolla in three or six parts, or if these 

 are absent, stamens and pistils without any envelope. This 

 division is named Petaloide^e. The second division contains 

 those plants which have no true calyx or corolla, but whose 

 parts of fructification are enclosed in imbricated scales or 

 bracts. These are the Glumace^e. All these classes, sub- 

 classes and divisions, together with the minor divisions which 

 are not so strictly natural, will be presented to the reader in a 

 tabular form, their points of distinction briefly recapitulated, 

 and examples of plants belonging to each of them mentioned, 

 so as to give at a single glance a clear idea of the whole. 



Before offering this, however, and before proceeding with 

 descriptions of the orders of the system, it is necessary that 

 the student should become somewhat acquainted with the 

 marks or characters used by botanists in determining these 

 orders, and should be able to estimate with some degree of 

 precision the value of these characters for that purpose. The 

 great advantage of some previous explanation of these will be 

 felt by the student when he comes to the perusal of succeeding 

 articles, and he must have the greater patience with what may 

 now seem to him dry and tedious, upon the assurance that his 

 future difficulties will be thereby materially diminished. He 

 will commence the study of the natural orders with an interest 

 and a pleasure heightened by the sense of having overcome 

 some of the chief obstacles to an acquaintance with them, and 

 his progress will be the more rapid in consequence of his pre- 



