On the Classification of Plants. 107 



Geological age — 

 Class 1. Found in tlie Lower Silurian age. 



2. First found in the Upper Silurian. 



3. First in tlie Devonian. 



4. First in the Carboniferous. 



So it will be seen that whether we regard the character of 

 the seed, the flowers, the leaves, the structure ; whether we 

 regard the mode of growth or the relative age of the world at 

 which each class was introduced, we equally find that, with 

 this arrangement, there is a regular progression from the more 

 simple to the more highly organized ; and fi'om the oldest to 

 the most recent. It is therefore the most natural and proper 

 classification of plants. 



But to find this regular progression we have been obliged to 

 disregard one character usually deemed of the highest import- 

 ance. Plants with the exogenous mode of growth are divided 

 and placed in two different classes. We are thus compelled, , 

 in this new classification, to consider the mode of growth or 

 internal structure of stems as of only secondary importance. 



The Grymnosperms are shown to be inferior to all the Angio- 

 sperms by their indefinite number of cotyledons ; by their 

 flowers without pistils ; by their dichotomously veined leaves, 

 which allies them with the ferns ; by their want of vascular 

 fibres in the structure of the stem ; and by the earlier epoch of 

 their creation. Hence it must be right to reduce these plants 

 to a position below that of the palms, the lily, and the orchids. 



When Cuvier found that the anatomy, the internal structure 

 of animals indicated their relative position in the scale of ani- 

 mal beings, the conclusion was very natural that the same law 

 existed with regard to plants ; and hence the prominence given 

 by De Candolle to the exogenous and the endogenous struct- 

 ure in his classification. But this must be regarded as one of 

 the most unfortunate ideas ever introduced into botany ; for it 

 requires that we rank the Gymnosj)erms above the Monocoty- 

 ledonous plants, though their affinities are thus clearly shown 



