22 OUTLINES OP PLANT LiPE. 



onies, plant cells may remain firmly united in rows or sheets. 

 Such an aggregation of cells is then called a plant. The 

 form of the plant depends upon the mode of division of the 

 cells. The body may be thread-like, and alike at both ends. 

 Or it may be distinguishable into a base and apex, or even 

 into a root-like part, the rhizoid, and a shoot-like part, the 

 thallus. Either may branch. Branching is due to more 

 rapid local growth of certain regions. In some plants the 

 protoplasm is not, or only incompletely, divided by cell- 

 walls. 



