192 HOW TO STUDY PLANTS. [LESSON 31. 



Sectioning the head of flowers vertically, as before, and turning to 

 page 130, we find that Series II., LIGULIFLOK^E, requires all the 

 corollas to be ligulate, as iu Figs. 221 and 222, which exactly 

 agrees with our Dandelion. 



556. The single tribe of this series, CicnoRiACE^:, is presented 

 on page 140, containing 12 genera. The first grouping depends 

 upon the nature of the pappus, and as every one knows that the 

 pappus of a Dandelion is of hair-like (capillary) bristles, the second 

 group is selected, "* * Pappus of capillary bristles, scabrous, 

 never plumose nor chaffy." In the three choices that follow, our 

 plant accords with the second, for in Dandelion the pappus is by 

 no means deciduous, nor are the akenes flattened, but it has 

 " Akenes not flattened : pappus persistent." Then follow two 

 choices based upon the akene having a beak or not. Turning to 

 Figure 296, page 130, we find a representation of our Dandelion 

 pappus, showing it raised away from the akene on a long beak. 

 This determines us to select " -M- ++ Beak to the akenes distinct 

 arid slender," etc. 



557. Three genera are thus presented for our selection. In the 

 first (Troxiinon) there is an imbricated involucre and a ten-ribbed 

 akene, but in Dandelion the involucre is composed of a single 

 series of nearly equal narrow bracts, with some small ones at 

 the base, and the akenes are only four or five-ribbed. In 

 Pyrrhopappus the pappus is not white, hence our choice must be 

 Taraxacum. 



558. Turning to page 222, we find but one species, and upon 

 reading it we are satisfied that it accords exactly with our plant, 

 which must be Taraxacum officinale, Weber. 



559. The old specific name Dens-leonis, which is meant to be 

 translated by our common name Dandelion, has disappeared, and 

 it will be noticed that it follows the specific description we have 

 just read as a synonym, that is, a former name of the plant which 

 has been discarded. The name officinale was substituted for Dens- 

 leonis because it was found to be an older name for the same plant ; 

 and when two or more botanists each give a name to the same 

 species, the law of nomenclature agreed upon requires us to retain 

 the oldest name and make synonyms of the rest. 



