THE VICTORIAN NATURALIST. 43 



separable into three or six parts. Exogens branch into three 

 groups, viz. — Pnlvpetals . in which the corolla is composed of at 

 least two pieces ; q-aniopetal s. in which the parts of the corolla are 

 combined so as to lorm a single piece ; and apetals, in which the 

 floral envelope is either single, the distinction of corolla and calyx 

 being lost, or is altogether wanting. Following these primary 

 divisions, are qrdex£, genera^ and species . As each of these groups 

 of plants is founded on characters common to a large number of 

 individuals, it is plain that if we can step by step eliminate such 

 characters as are foreign to tlie particular specimen we have in 

 hand, retaining those only which belong to it as aa individual, we 

 shall gradually isolate it from its surroundings and ascertain its 

 name. It is on this principal that the system adopted in the 

 following pages is based. However, as 'example is better than 

 precept,' we will suppose that the reader is desirous of ascertaining 

 the name of a plant, which turns out to be the well-known clematis, 

 so frequently met with in tlie bush, decorating the trees and shrubs 

 w'lVa its white stariy flowers. Turning to the first pair of con- 

 trasted characters on page 1, we read as follows : — 



1. Flowering plants, having stamens, pistils, and seeds. Pluenogams 2. 

 „ Flovveiiess plants, &c. Cryptogams 123. 



Ours is of course a flowering plant or phaenogam, after which is 

 placed the figure 2, so to that number we turn : — 



2. Veins of leaf netted. Flower in four or five parts, &c. Exog^ens 3. 



„ Veins of leaf parallel. Flowe- in three or six parts, &c. Endogens 107. 



A glance at the leaves shows a surface of closely netted veins, and 

 the flower is divided into four, occasionally five parts ; hence the 

 plant is an exogen, and we go to number 3 : — 



3. Corolla and calyx distinct : the former usually conspicuous. 4. 

 „ Corolla and colyx indistinguishable or wanting. Apetals 78. 



There being but one floral envelope comprising both corolla and 

 -calyx, the specimen is apetalous ; we therefore pass at once to the 

 bracket marked 78 : — 



78. Stipules entirely or half sheating the stem, &c. 79. 



79. Stipules normal or wanting. 80. 



There are no stipules ; 80 therefore is the next number to be looked 

 for : — 



80. Perianth conspicuous, &c. 81. 

 „ Perianth obscure, &c. -83. 



As the white perianth is decidedly conspicuous, we clioose 81: — 



81. Stamens numerous, inserted under ovary, styles several, <kc. Ranun- 



culefe. 127. 

 ,, Stamens two or four inserted on perianth. Style 1, &c. 82. 



The numerous stamens and styles show that we have reached the 

 riglit natural order, ranunculea; . The ne.xt point is to determine 

 the genus. Fer this we are directed to 127 — 

 127. Leaves opposite, .&c. Clematis. 514 

 ,, Leaves alternate or radical, &c. 128. 



