THE PTERIDOPHYTES. 



iSITY J 

 V 





FIG. 117. Part of a transverse section 

 of the rhizome of Pteris aquilina. 

 A, A, fibro vascular bundles; B, fun- 

 damental parenchyma; C, sclerotic 

 parenchyma or hypodermis. 



all portions of the plant 

 that do not contain chlo- 

 rophyl. The fibro vascular 

 bundles form continuous 

 conduits from the small- 

 est rootlets up through 

 the rhizome and stipe, and 

 send their branches into 

 the divisions and sub- 

 divisions of the leaves. 

 Externally they may be 

 traced as the ribs and 

 veins of the leaves. The 

 possession of the fibro- 

 vascular bundles forms, as already stated, a marked line of 

 separation between the cellular plants of the lower sub- 

 divisions and the vascular plants of the Pteridophytes and 

 the higher Flowering Plants. 



4. Examine under low power a 

 cross section of the rhizome. Draw 

 the section and locate by letters 

 the epidermis, hypodermal tissue, 

 ground parenchyma, sclerenchyma, 

 bundle sheath, scalariform and spiral 

 vessels, and intercellular spaces. 



Treat a section with Schultze's 

 solution. Draw, and locate by let- 

 ters the portions containing lignified 

 cellular tissue. 



Treat a section with iodine solu- 

 tion. What tissues contain starch? 

 These tissues serve as storehouses 

 for the reserve food of the plant. 

 Stain a section, cut after imbedding 

 in celloidin, in picro-carmine for 



FIG. 118. Diagram show- 

 ing the branching and 

 interlacing of the h'bro- 

 vascular bundle in the 

 upper side of the rhi- 

 zome of Pteris aquilina. 

 I shows the origin of a 

 leaf. (After Sachs.) 



CLARK'S BOX. 13 



