48 ELKMKNTS OF BOTANY. 



in flio Icnnwn wcirM liaviiif? tlio pfpiicral Htrnctiivfi of a pontiaii, conipriHing 

 many ^ciuM'a, as t/cnlidiiii, fdhlxili'i, J'nist'ra, vtc. 



Tlio f^fonns cjentiana iucludfcH all the gentiauH, nud their names are 

 •written thus : 



Gontiana quiiuincflnra Laniarch — Five-flowored gentian. 



(Jcntiana criiiita Frnclich- Fringed gentian. 



(lentiana Antlrewsii (Irisebach — Aiidrows' gentian, etc. 



Th(! words Fianian-k, Froelieh, and (Irisebach being the names of the 

 botanists who described the plants and gave them their si)e('itic names. 



Such is a l)rief outline of the classiticjation of plants at present em- 

 ployed. It is variously modified to suit circmnstances, but these modifi- 

 cations do not recpiire our attention here. There is, however, one point 

 which re(|uires a passing glance. T^ speaking of species, these were 

 treated of as being absolutely distinctive. Now, in reality this is far from 

 the fact, for often species — as described — are diflicult to distinguish one 

 from anothei'. Again, the same sjjeciea may present plants of, in some re- 

 spects, dillerent aspects ; as for example, a plant whose flowers are habitu- 

 ally blue may produce individuals with white Dowers. Now when such 

 variations from the spcn-itic standard tend to rejjrochice themselves year 

 after year, they are termed varieties ; hence we not unfrequently see the 

 specific name f(jllowed by the word variety and another name, as Anemone 

 patens Linne, var. NitttaUiava Gray, signifying that the plant is a varietj' of 

 anemone i)atens as characterized by Linm', which variety was named for 

 Nuttall and descril)ed by Gray. 



The i)lants of any region or coinitry arranged systematically according 

 to this — or any other — system of classification is termed the flora of that 

 region or country, and such a flora is of immense service to the student 

 who wishes to familiarize himself with the plants about him. AVith this 

 flora before him and an unknown plant in his hand, he is enabled to trace 

 out analytically, stej) by step, the relationship of the unknown with the 

 known, and finally to fix the plant's specific location. 



We will suppose him with a flowering plant in his hfind, but one which 

 he has never seen before. He begins by ascertaining whether it be ex- 

 ogenous or endogenous ; if exogenous, whether polypetalons, gamopeta- 

 lous, or apetalous ; and then whether it bear evident relationship to plants 

 of any order with which he is familiar. If not, he must search through 

 the characters of orders until he can fix its ordinal location, then its ge- 

 neric place, and finally its specific name. For facilitating such analyses arti- 

 ficial keys are supplied in most published fioras. 



A medical flora, such as is attempted in the second part of this volume, 

 is an orderly arrangement of the medicinal plants of any region or country. 

 Obviously a key cannot readily be availed of in such a work, for, to be of 

 any service, it must be capable of application to all the plants which the 

 territory includes. 



