DESCRIPTIVE BOTANY. 151 



however, we willingly abbreviate, as Thlaspi Bursa Pastoris, 

 Hedysarum Caput galli, Lysimachia Linum stellatum, 



III. Delineation of Characters. 

 228. 



Next to nomenclature, the delineation of characters is the 

 most important part of phytography. But we must under- 

 stand the method of delineating, and of correctly expressing 

 both generic and specific characters. This demands the ob- 

 servation of some general rules, which we are about to state. 

 The most essential requisite in a good character is, that it be 

 expressed in the generally understood technical language, and 

 neither contain undefined terms, nor comparisons with other 

 plants, or with other objects of nature and art. Comparison 

 and metaphorical expressions are objectionable on this ground, 

 that the character must give a positive acquaintance with the 

 object. But from this rule those terms of comparison are 

 excepted, which are of common use in the artificial language. 



229. 



It is also principal maxim in the delineation of characters, 

 that we should abstain from the introduction of all accidental 

 and non-essential things, because these lead only to confusion, 

 and are by no means invariable. 



Into the character of genus and species we must admit only 

 those marks which distinguish plants from those that are re- 

 lated to them. This may be done v/ithout instituting com- 

 parisons, which belong much rather to the description and 

 diagnosis. The sum of the marks which are found in rela- 

 ted plants, must always be before us whilst we are delineating 

 the character ; on which account it is impossible to give the 

 character of a new genus or species, unless we know the plants 

 which have a similar nature. 



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