UNLIKE PLANTS GROW TOGETHER 



221 



have other plants to gain a foothold. When the wheat com- 

 pletely covers the ground, as in Fig. 384, there are no weeds 

 to be seen. 



379. Plants of different form and habit may grow 

 together, and thereby the area may support more plants 

 than would be possible if only one kind were growing on 

 it. This principle has been called by Darwin the divergence 



388. A primeval pine forest. 

 Along the roadway foreign vegetation has come in. Michigan. 



of character. When an area is occupied by one kind of 

 plant, another kind may grow between or beneath. Only 

 rarely do plants of close botanical relationship grow to- 

 gether in compact communities. A field that is full of corn 

 may grow pumpkins between. (Fig. 385.) A full meadow 

 may grow white clover in the bottom. Herbs may grow 

 on the forest floor. When an orchard can support no more 

 trees, weeds may grow beneath. 



