INTRODUCTION. 



BY CHARLES E. BESSEY, PH.D. 



The Vegetable Kingdom is in other words the plant world, or the aggregate of organ- 

 isms called plants. It is co-ordinate with the animal kingdom, and these two include all 

 forms of organic life on the earth. It is not possible to define precisely the line which 

 separates the lower portions of these two kingdoms; we may therefore regard them as 

 simply branches of one great group, inseparable below, but widely divergent above. In 

 attempting to separate plants from animals the most we can do is to bring together t hose 

 characters which separate the greater number of plants from animals, and then to asso- 

 ciate with the plants thus set off such of the remaining organisms as appear to be more 

 plant-like than animal. 



For the most part plants are cells enclosed in walls of cellulose, or aggregates of 

 such cells, all or part of which contain chlorophyll, by means of which they are able to 

 appropriate carbon from inorganic matter (carbon dioxide). The organisms thus set off 

 constitute the bulk of the vegetable kingdom, and characterize its principal divisions. 

 With these typical plants we must associate many which have lost some of their strictly 

 vegetable characteristics through parasitism or saprophytism. Thus the thousands of 

 species of fungi, while destitute of chlorophyll and incapable of appropriating inorganic 

 carbon, are plants nevertheless, and are to be associated with those to which they show 

 some structural similarity. 



There are now known and described about 175,000 species of plants on the globe, ana 

 recent estimates made by Professor Saccardo show that this is probably loss than one-half 

 of the total number. This vast assemblage of organisms requires classification in order 

 that we may study them and communicate our results toothers. Accordingly similar 

 species have been gathered into genera, similar genera into families, similar families into 

 orders, etc. Finally we have been able, from a study of these groups, to make generalis a 

 tions as to their probable relationship, and thus to form a genetic Bystem in which all 

 plants are included in six great branches, further subdivided into dfteen GLASSES. This 

 system may be graphically represented by the accompanying diagram. 



In the synopsis of the Flora of Nebraska presented below, the sequence is from prim- 

 itive or simple forms to those which are derived or more complex. It will be seen by a 

 comparison of the synopsis, with the diagram given above, that many cases occur in which 

 several groups have had a common origin from which they have diverged, their highest 

 forms differing most widely. It follows therefore that in the synopsis we are compelled 

 to return again and again to these common points of origin in order to follow out suc- 

 cessively the diverging genetic lines. 



But it must not be forgotten thai the derived forms have suffered degradation, as is 

 notoriously the case with the fungi and other parasitic or saprophytic plant-. Here the 

 degraded form is the derived one, and accordingly it must be considered after the primi- 

 tive form, although the latter may be actually more complex. In the dowering plants we 



