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PHARMACEUTICAL BOTANY 
minute and simple structure, being merely elongations of the 
epidermis of the root back of the root cap into slender tubes with 
thin walls. 
Fig. 57.—Cross-section of rootlet in the region of the root-hairs. ( From Stevens.) 
The tip of each rootlet is protected by a sheath- or scale-like cover¬ 
ing known as the root cap, which not only protects the delicate grow¬ 
ing point, but serves as a mechanical aid in pushing its way through 
Fig. 58.—Root-hairs, with soil-particles adhering. (Gager, after Sachs.) 
the soil. The generative tissues in the region of the root cap are: 
plerome, producing fibro-vascular tissue; periblem, producing cortex; 
dermatogen, producing epidermis; and calyptrogen, producing the 
root cap. 
