48 NATTJBAL OBDEES. 



Akeangement op the Natueal Oedees in the peesent Woek. 



T)ie very unequal manner in which the several Natural Orders are repre- 

 sented in the British Isles, renders it impossible, in a work confined to 

 British plants, to give any fan* idea of the subclasses into which these Orders 

 have been grouped, or of the principles which have guided the authors of 

 the linear arrangement the most generally followed. The following re- 

 capitulation is therefore merely intended as a sort of table of contents, show- 

 ing the order in which the families follow each other m the present work ; 

 at the same time that the attention is called to one or two of the most 

 striking, the most important, or the earhest observed features of each one. 

 These characters are however general, not always without exception, and 

 sometimes specially applicable to British genera only. 



CLASS I.-DICOTYLEDOIfS. 



In the germination of the seed the plumula arises between two (rarely 

 more) lobes or cotyledons of the embryo, or fi-om a terminal notch. 



Subclass 1. Thalamifloebs. — Petals distinct from the calyx, and from 

 each other, seldom wanting. Stamens hypogynous. 



* Ovary apocarpous. 



I. Ranuneidus family. Petals definite. Stamens indefinite. 



II. Barberry famUy, Perianth and stamens in twos or threes, or^ their 

 multiples. Anthers opening by recurved valves. 



III. Waterlify family. Aquatic plants with indefinite petals and stamens, 

 the inner petals passing gradually into the outer stamens. 



** Ovary syncarpous. Placentas parietal. 



IV. Poppy family. Perianth regular, in twos or fours. Stamens in- 

 definite. 



V. Fumitory family. Perianth very irregular, in twos or fours. Stamens 

 6, in two sets. 



VI. Crucifer family. Sepals and petals 4 each. Stamens 6, of which 2 

 shorter. 



VII. Mignionette family. Petals small, unequal, some divided. Sta- 

 mens few but indefinite. Capsule open at the top before it is ripe. 



VIII. C'istus family. Sepals 3, equal, or with additional smaU ones. 

 Petals 5, regular. Stamens indefinite. 



IX. Violet family. Stamens 5; the anthers on the inner face, of very short 

 broad filaments, usually miited in a ring. Capsule three-valved. 



X. Frankenia family. As in tlie Pink family, except the parietal pla- 

 centas. 



*** Ovary syncarpous. Placentas axils. 



XI. Pink family. Leaves opposite, entire. Flowers regular. Stamens 

 definite. Capsule one-celled, with a fi-ee central placenta. 



XII. Elatine family. As in the Pink family, but the capsule divided into 

 cells. 



XIII. Tamarisc fanuly. Shrubs with alternate green scale-like leaves. 

 Flowers regular. Capsule one-celled. Seeds with a tuft of wool. 



XIV. Hypericum family. Leaves opposite. Flowers regular. Sepals 

 imbricate. Flowers indefinite, in 3 or 5 clusters or bundles. 



