BOTANICAL SUBJECTS. Uo 



reproductive head consisting of peltate shields, which do not differ 

 materially from the indusia of ferns. 



Let us make a comparison of these two very distantly related 

 plants — the Monarda and the Equisetum. The calyx of the 

 Monarda is almost indistinguishable from the leaf-sheath of the 

 horsetail. Instead of a stem within the calyx, it has a whorl of 

 fused petals ; within that a whorl of stamens, and then a whorl 

 of carpels. The flowers of each whorl correspond to the branches 

 round each node of the horsetail. The difference is that in the 

 horsetail the nodes and whorls are repeated ad infinitum^ much as 

 the whorls of the Primula j aponica are repeated at intervals on 

 its stem ; while in the Monarda the flower axis is very short, and 

 the internodes are obliterated. 



The essentials are the same throughout, but they admit of 

 much variation. The Monarda has leaves proper and involucral 

 bracts, which are entirely suppressed (or have never developed) in 

 the horsetail. The calyx sheath is coloured, so is the corolla 

 sheath ; while in the horsetail the sheaths are repeated without 

 variation. The whorl of branches in the horsetail corresponds 

 to the whorl of flowers in the Monarda, while the central stem* 

 is repeated only once, if at all, in the Monarda, carrying at its 

 apex another flower head. As the leaves proper in the horsetail 

 are suppressed, its energy is expended on a repetition of stems. 



In the course of the following pages it will be seen that I have 

 little regard for the classification of plants, at which many 

 botanists have worked for ages ; not because it is not of great use, 

 for classification has for its basis a common descent, and therefore 

 a proof of evolution, but because it is an artificial mode of 

 grouping natural affinities. This would seem a paradox. The 

 alliances are natural enough for the reason that the members 

 composing them have probably branched off from a common centre 

 of parentage. But, owing to the extinction of many groups in the 

 race for life, there are gaps between groups which might lead the 

 student to think that these different groups had little or nothing 

 to do, in origin, with each other. 



In order, however, to show what modern naturalists think 

 about evolution, I shall end this part by quoting a passage from 

 C. F. Holder's " Life of Darwin," p. 203. 



* In the specimen uuder obser%''ation and in those I saw at Kew. 



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