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rely upon the same characters or set of characters for the de- 

 termination of species in all cases. How then are we to pro- 

 ceed ? We must look elsewhere ; and thus we are compelled 

 to seek for more permanent distinctions in habit or in the 

 morphological characters of plants, a branch of the science 

 much neglected, but one which will amply repay the scientific 

 enquirer for the labour of his investigations ; for only a casual 

 acquaintance shows the unerring constancy of certain forms of 

 growth, colour, or hue, in certain species, characters which 

 they retain under all circumstances and in every state. For 

 instance, what two plants can be more distinct than the Silene 

 injlata and 8. maritimi, already referred to ? The upright 

 mode of growth of the former, as compared with the repent 

 habit and crowded state of the leaves in the latter, would suf- 

 ficiently characterize the two plants at any time. Then again, 

 in Echium vulgare, Linn., we find a most decided distinction 

 in the lateral spikes of flowers, whereas in E. violaceunij Linn., 

 its near ally, the spikes of flowers are to a great extent 

 panicled. The erect and rigid frond of 'Polypodmm calca- 

 reum, Sm., is quite suflicient to distinguish it from its more 

 graceful congener P. Bryoptens, Linn., without even having 

 recourse to the glandular scales of the former. 



But, while we admit that great, very great, value must be 

 placed on the habit of plants in describing the characters of 

 nearly allied species, it cannot be denied that great care is 

 requisite to guard against carrying this principle too far : for, 

 although such characters when used with discretion are most 

 valuable, the reverse might be the case if universally adopted. 



By these characters alone we distinguish plants apart from 

 the science of botany ; and it is by the same characters that 

 plants are distinguished by the uninitiated. If therefore there 

 is so marked a distinction in the habit of individuals, it 

 appears quite evident that we may reduce those characters to 

 system. But we must recollect that nature presents no arti- 

 ficial system, but one uniform series of individuals, from the 



