54 BOTANY. 



E. Class XIX. subdivides into : 



Order 1. Polygamia aequalis: florets all hermaphrodite. 



" 2. " superflua : florets of the disk hermaphrodite, those of the 



ray pistilliferous and fertile. 

 " 3. " frustranea : florets of the disk hermaphrodite, those of the 



ray neuter. 

 " 4. " necessaria : florets of the disk staminiferous, those of the 



ray pistilliferous. 

 " 5. " segregata : each floret having a separate involucre. 



" 6. Monogamia. Anthers united, flowers not compound. 



F. Classes XX. to XXII. subdivide into : 



Orders: Monandria, Diandria, &c., according to the number of stamens. 



G. Class XXIII. subdivides into : 



Order 1 Monoecia : Hermaphrodite, staminiferous, and pistilliferous flowers on 

 the same plant. 

 " 2. Dioecia : the same on two plants. 

 " 3. Trioecia : the same on three plants. 

 H. Class XXIV. subdivides into : 



Order 1. Filices: Ferns. 

 " 2. Musci: Mosses. 

 " 3. Hepaticae : Liverworts. 

 " 4. Lichenes: Lichens. 

 " 5. Algfe : Seaweeds. 

 " 6. Fungi : Mushrooms. 



The object in the natural system is to combine those plants which are 

 allied in essential points of structure. Every natural method is, hoAvever, 

 to a certain extent artificial, and it Avill be impossible to construct a perfect 

 natural system until all the plants of the globe are known. The first natural 

 system of much special value was that of Jussieu, published in 1789. This 

 includes one hundred natural orders or groups of genera, the whole arranged 

 under fifteen classes, as follows : 



Natural System according to Jussieu. 



ACOTYLEDONES, 



f Mnno-hypogyncc (Stamens hypogynous), . 

 MoxocoTYLEDONES, \ Mono-perigymc ( " perigynous). 



(^ Mono-epigyncc ( 



epigynous). 



Class 



I. 



II. 



III. 



IV. 



DlCOTYLEDONES, 



A petal re 

 (No petals) 



{Epistaminea) (Stamens epigynous) V. 

 Peristamineffi( " perigynous) VI. 

 Hypostaminese ( " hypogynous) VII. 



''Hypocorollae(Corollahy pogynous)VIII. 

 Perieorollse ( " perigynous) IX. 



Monopetalse < 

 Monoclines ^ (Petals united) 

 (flowers united) 



Epicorollaj 

 (Corolla epigynous) 



Synantherffi 

 (anthers united) 



X. 



Corisantheraj . XI. 



(anthers free) 



rEpipetalse (petals epigynous). XII. 



Polypetalae \ Peripetalae ( " perigynous). XIII. 



(Petals distinct) ^^Hypopetalse( " hypogynous). XIV. 



Diclines (flowers unisexual or without a perianth). . . XV. 



54 



