100 PHARMACEUTICAL BOTANY 



of more or less rounded cells having delicate cell walls of cellulose 

 which enclose protoplasm and nucleus and wherever found in living 

 embryos are in a rapid state of division. 



The generative tissues are found in the growing apices of plant 

 organs, such as root, stem and leaf apex. By the division and redivi- 

 sions of their cells they give rise to the mature or adult tissues of 

 plants. 



1. Dermatogen originates epidermal tissue and derivative struc- 

 tures such as stomata, non- glandular and glandular hairs, glands, 

 and cork cambium. 



2. Periblem originates cortex tissue, chlorophylloid cells (chlor- 

 enchyma) colloid cells (collenchyma), strengthening cells (scleren- 

 chyma), crystal cells (raphiderchyma) latex cells (lacterchyma), 

 endodermis and cork cambium. 



3. Plerome originates fibre-vascular bundles, fundamental tissue, 

 pericambium and cambium. 



According to structure the following tissues are found in various 

 forms of higher plants: 



1. Meristem 7. Cork 



2. Parenchyma 8. Laticiferous tissue 



3. Collenchyma 9. Cribiform or sieve tissue 



4. Sclerenchyma 10. Tracheary tissue 



5. Epidermis n. Medullary rays 



6. Endodermis 



MERIS1EM 



Meristem, frequently called embryonic tissue, is undifferentiated 

 tissue composed of cells -in the state of rapid division. It is found 

 in the growing apices of roots, stems and leaves and is in these 

 regions called primary meristem, since it is the first meristem to 

 appear. Such meristem gives rise to the permanent or mature 

 tissues of plants and retains the power of independent growth and 

 capacity for division as long as the plant part survives which con- 

 tains it. Meristem is also found in other regions of plant organs 

 such as the cambium, cork cambium and pericambium and is there 

 called secondary meristem. Secondary meristem loses with its de- 

 velopment the power of division and independent growth. 



