l4 NOMENCLATURE 



When plants of the same kind have different shapes, they 

 are said to be dispares. DimorpJms is the word applied to 

 one and the same part, which has different forms in the same 

 plant. An organ is called diffbrmis, when its shape cannot 

 be reconciled with the usual form of the part. 



II. The Colours of the Parts, 

 21. 



As colour produces an impression upon the senses which is 

 universal, it cannot be precisely defined, nor can it be em- 

 ployed as a character of the invariable Species. It is chiefly 

 of use, therefore, in description. Yet we must put a great 

 value even on this, when we are treating of the lower organic 

 bodies, where other characters fail, and where those derived 

 from colour are very stedfast. 



There are two colours, which have been usually considered 

 as essential, and whi^h have, hence, been universally taken as 

 characters. These are the hoary^ {canus^ incanus) ; the 

 weaker variety of which is called canescens^ and the greenish- 

 blue (glaucus)^ the weaker gradation of which is named 

 glaucescens. 



Besides, it is usual, when the ordinary green colour of the 

 integument of the leaves fails, to express this simply by the word 

 coloured, (coloratus) ; and when there is a difference of colours, 

 as, for instance, on the two sides of the leaves, we employ the 

 word discolor, as in Cornus alba. The opposite is, therefore, 

 unicohr, that is, when the colours are of the same kind. 



A difference of colouring is also expressed generally by the 

 words spotted (maculatus), variegated (variegatus), and by 

 the words notatus and sphacelatus. The former expresses a 

 dark spot ; the latter the swarthy discolorations, which are 

 yearly the consequences of the decay of the parts. We use 

 the word zonatus to express differently-coloured curved lines 

 upon a surface : marginatus signifies that the margin is dif- 



