BOTANY. 



II. NATURAL SYSTEM. 



Class I. — Exogens, or Dicotyledonous Flowering Plants, 



Leaves reticulated. Stem with bark, wood, medullary rays, and pith ; increasing in 

 diameter by the addition of new matter to the exterior. Flowers with a quinary, or 

 more rarely a quaternary, division. Seeds in a pericarp. Cotyledons two, opposite ; 

 or, if more, whorled, or on the same plane. Germination exorrhizous. 



1. Divisions of Jussieu.— The primary divisions are founded on the separation, 

 the combination, and the absence of the petals, and are termed the polypetalous, the 

 monopetalous, and the apefalous groups ; to which is added a fourth, founded on the 

 separation of the sexes in flowers having no petals, and termed diclinous. The first 

 three are divided with reference to the insertion of the stamens, which are epi- 

 gynous, perigynous, or hypogynous ; further, the monopetalous epigynous group is 

 subdivided into plants which have their stamens united and those which have them 

 distinct. Hence we have eleven classes : — 



Class. 



{Stamens epigynous 1 

 Stamens perigynous 2 

 Stamens hypogynous 3 



< Corolla hypogynous 4 



^Corolla epigynous {Anthers distinct 7 



{Stamens epigynous 8 



Stamens perigynous 9 



Stamens hypogynous 10 



Diclinous 11 



2. Divisions of Be Candolle. — De Candoile reduced the eleven classes of Jussieu 

 to four ; the first three being founded on the separation or cohesion of the several 

 parts of the flower, the fourth on the suppression of the floral envelopes. Thus, in 

 Thalamiflorae, all the parts are present and distinct from each other ; in Calyciflorae, 

 the stamens adhere to the calyx ; in Corolliflorae, the petals cohere with each other; 

 in Monochlamydeae, the corolla is suppressed, and, in the most imperfect orders, the 

 calyx also. 



PnlvnPtalmi«! /^*^™®"S hypogynous Thalamifforce. 



rojypeiaious j gj^^^gj^g perigynous Calyciflora;. 



Monopetalous CoroUiJlorai. 



Apetalous Monochlamydece. 



3. Divisions of Dr. Lindley. — Dr. Lindley first distributes the Class into the 

 Polypetalous, Monopetalous, and Incomplete sub-classes ; these are next divided 

 into groups. The principles on which these divisions are founded are stated in the 

 following table : — 



Table of Groups. 

 Sub-class I. Polypetalae. Groups. 



Albumen very considerably larger than the minute embryo AlbuminoscB. 



Albumen absent, or only forming a layer between the embryo and 

 the seed-coat. 



Ovary inferior (often with an epigynous disk) Epigynosee. 



Ovary superior. 



Placentae parietal Parietosa. 



Placentae in the axis. 



Calyx dislocated Calycosee. 



Calyx complete ; its parts being all on the same plane. 

 Carpels united into a solid pistil, parallel with 



each other Syncarposa. 



Carpels oblique, upon a gynobase Gynobaseosce. 



Carpels disunited Apocarposce, 



58 



