266 Education through Nature 



ADAPTATIONS OF STEMS TO WORK. 



o 



I 



I 



i. Climbing 



2. Storage 



3. Circulation- 



4. Support 



1. Roots at many joints 



2. Production of tendrils 



3. Twisted petioles or leaf -stalks 



4. Slender stems for climbing 



1. Underground position 



2. Thickened and fleshy 



3. Corky bark to prevent evaporation 



4. Pithy 



1 . Fibro vascular bundles 



2. Cambium layer 



3. Sieve -tubes and tracheids 



4. Thickened walls of wood-cells 

 . 5. Medullary rays 



1. Heart wood of trees 



2. Hollow stems of grasses 



3. Hard wood and bast-tissue 



TISSUES OF STEMS. 

 ' i . Epidermal tissue 



Exogens 



but 



CELLS OF PLANT TISSUES. 



13. Forms of Plant -cells 



1. Spherical 



2. Cylindrical 



3. Flat 



4. Spindle-shaped 



5. Hexagonal 



6. Elongated 

 ,7. Irregular 



