CHAPTER XXXIV. 



THE PLANT BODY AND SOME OF ITS MODI- 

 FICATIONS. 



For reading and reference. 



If it is desired to study the different kinds of stems, leaves, 

 and roots, with their various modifications, the teacher can 

 arrange some exercises based on the characters and examples 

 given below in paragraphs 358-364. 



356. The plant body. — In the simpler forms of plant life, as 

 in spirogyra and many of the algse and fungi, the plant body is 

 not differentiated into parts. In many other cases the only 

 differentiation is between the growing part and the fruiting part. 

 In the algae and fungi there is no differentiation into stem and 

 leaf, though there is an approach to it in some of the higher 

 forms. Where this simple plant body is flattened, as in the 



isea-wrack, or ulva, it is a frond. The Latin word for frond is 

 thallus, and this name is applied to the plant body of all the 

 lower plants, the algae and fungi. The algae and fungi together 

 are sometimes called the thallophyies, or thallus plants. The 

 word thallus is also sometimes applied to the flattened body of 

 the liverworts. In the foliose liverworts and mosses there is an 

 axis with leaf-like expansions. These are believed by some to 

 represent true stems and leaves, by others to represent a flattened 

 thallus in which the margins are deeply and regularly divided, 

 or in which the expansion has only taken place at regular 

 intervals. 



357. Members of the plant body. — In the higher plants there 

 is usually great differentiation of the plant body, though in 



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