OCCUPATION OF LAND. 



303 



tected by man occupy cultivated fields. When cultivation 

 ceases, or the crop is removed, or the fields are neglected, 

 hundreds of species of feral plants, which are constantly spring- 

 ing up, now nourish, bear seed, and take more or less complete 



Fig. 254. 

 Abandoned field, Alabama, self reforested by pines. (Photograph by Prof. P. H. Mell.) 



possession of the soil. Impoverished land, abandoned by man, 

 becomes nurtured by nature. Weeds, grass, flowers spring up 

 in great variety often. Some can thrive but little better than 

 the abandoned crops, while others, peculiarly fitted because of 

 one or another adapted structure or habit, flourish. Crab-grass 



