LKSSOX 31.] H^W TO STUDY 1'LANTS. 191 



characters as given there confirm our choice. Tlie five genera of 

 Senecionidese are arranged in four groups, indicated by asterisks, 

 all based chiefly upon the character of the involucre. No charac- 

 ters agree with our plant until we reach " * * * # Involucre of 

 numerous or several coimivent-erect herbaceous equal bracts, many- 

 flowered: herbs, with opposite or alternate leaves." The choice 

 now lies between the two genera Arnica and Senecio, and the 

 copious soft pappus and alternate leaves indicate the latter. The 

 character of the involucre of Arnica also refers our plant to 

 Senecio in a negative way. Accordingly we turn to the 70th 

 genus, SENECIO, page 20G, and find under it 21 species. 



554. The first grouping of species, marked by asterisks, depends 

 upon the size of the heads, and as ours do not by any means 

 measure half an inch in height, the second group is selected 

 (p. 207). Then follow two choices, indicated by daggers, the 

 second of which, " H *- Heads erect, mostly radiate," agrees with 

 the plant in hand. The four groups that follow, under double 

 daggers, <--> on page 207, ++ ++ and *-+ -H- -n- on page 208, and 

 .n* ++ -H- .H. 011 p ; ,g e 211, being carefully read, lead us to select 

 the third, * +* ++ ++ Stems either few-leaved or with the upper 

 leaves reduced in size ; the inflorescence therefore naked : none 

 with narrow linear leaves." Under this two choices are marked 

 by parallels, but the first is at once rejected on account of the 

 character of its leaves. Under = = (p. 209) three groups are in- 

 dicated by the letters a, b, and c. Our plant is too slender and 

 low, and its leaves too deeply cut, for the first ; while it is too tall 

 for the second, besides being entirely unlik& it in habit. We ac- 

 cordingly select the third division, c, and under it find two choices 

 based upon leaf characters. As none of our leaves are *' pinnately 

 divided," we decide upon the group marked 1, and must now make 

 a choice of three species, 17. 18, or 19. The great probability is 

 that the choice will fall upon number 18, or one of its varieties, 

 and so, by this long but comparatively easy route, we find that our 

 plant is Senecio aureus, L., the commonest of all the Golden Rag 

 worts. Many other species of this genus are found on the plains, 

 and in the highest mountains up to their very summits, but the 

 genus should now always be easily recognized by such characters 

 as are furnished by its involucre, pappus, alternate leaves, etc. 



555. As an example of the other series of Composite, no more 

 common or simple plant could be selected than the Dandelion. 



