CHARACTERS USED IN CLASSIFICATION. 175 



7th. Constant characters may be isolated or coexistent. The 

 petals of the RANUNCULUS acris (butter-cup) have a nectary in 

 the form of a scale ; this character, although constant, is iso- 

 lated, for it is not necessarily connected with any other char- 

 acteristic trait. The calyx of the campanula rotundifolia^ 

 (blue-bell,) adheres to the germ ; the germ must of necessity 

 be simple, or without divisions, and the corolla and stamens 

 attached to the interior of the calyx. The character of the 

 adherence of the calyx to the germ, brings in its train several 

 other characteristics ; it is then coexistent; and is more impor- 

 tant than the isolated character. 



8th. Two orders of characters are derived from the two great 

 divisions of vegetable organs ; those of vegetation and repro- 

 duction. The characters of vegetation are few, and mostly 

 isolated the characters of reproduction are numerous and often 

 coexistent ; one character serving as an index to many others. 



It is seldom that plants which resemble each other in their 

 characters of reproduction, differ much in their characters of 

 vegetation. For example, all plants which have four didyna- 

 mous* stamens, attached -to a mo uopetalous labiate corolla, and 

 four seeds lying uncovered in a monophyllous calyx, have an 

 angular stem and opposite leaves. On the contrary it frequent- 

 ly happens, that plants which resemble each other by the 

 characters of vegetation, differ by those of fructification. 

 Labiate and caryophyllous plants agree in having their leaves 

 opposite, and yet there is no resemblance in their flowers. 

 This consideration alone, would seem sufficient for establishing 

 the superior importance of the characters of reproduction 

 over those of vegetation. The seed unites in itself the char- 

 acters both of reproduction and vegetation. The embryo is 

 the commencement of the new plant, and it offers us the first 

 characters of vegetation ; but its situation in the fruit, the 

 number, form and consistence of its envelope, are characters 

 which belong to fructification. 



As far as possible, in separating or bringing together plants, 

 we should make use of prominent characters which the eye 

 can see, without the help of the microscope ; but if experience 

 teaches us that the characters most constant and proper for the 

 explanation of physiological phenomena can only be discover- 

 ed by such aid, it is necessary to resort to this instrument, in 

 order to establish the natural relations of plants.f 



* That is, two long and two short stamens. 



t The foregoing rules and observations respecting characters for classifica- 

 tion, are translated from Mirbel's " Elemens de Botanique." 



The seventh ? The eighth ? Characters of reproduction more important 

 than those of vegetation In what cases should we make use of characters 

 invisible to the naked eye? 



