3^4 RELATION 7^0 ENX'IRONMENT. 



714. Physiological Classification of Tissues. 



Formative Tissue. 



Thin-walled cells composing the nieristem, capable of division and from 

 which other tissues are formed. 

 protective Tissue. 



Tegumenlary System. — Epidermis, periderm, bark protecting the plant 

 from external contact. 



Mechanical .System. — Bast tissue, bast-like tissue, collenchyma, scler- 

 enchyma, afford protection against harmful bending, puUing, etc. 

 Nutritive Tissues. 



Absorptive System. — Root hairs and cells, rhizoids, aerial root tissue, 

 absorptive leaf glands, absorptive organs in seeds, haustoria of para- 

 sites, etc. 



Assimilatory Syst.em. — Assimilating cells in leaf and stem. 



Conductive System. — Sieve tissue, tracheary tissue, milk tissue, conduct- 

 ing parenchyma, etc. 



Food-storing System. — Water reservoir, water tissue, slime tissue, fleshy 

 roots and stems, endosperm and cotyledons, etc. 



Aerating System. — Air spaces and tubes, special air tissue, air-seeking 

 roots, stomatcs, lenticels, etc. 



Secretory and Excretory System. — Water glands, digestive glands, resin 

 glands, nectaries, tannin, pitch and oil receptacles, etc. 

 Apparatus and Tissues for Special Duties. 



Holdfasts. 



Tissues of movement, parachute hairs, floating tissue, hygroscopic tis- 

 sue, living tissue. 



For perceiving stimuli. 



For conducting stimuli, etc. 



