14 PHARMACEUTICAL BOTANY 



(o) Concentric, with xylem central in bundle. Seen in stems and 

 leaves of nearly all ferns and the LycopodiacecB. 



(b) Concentric, with phloem central in bundle. Seen in stems and 

 leaves of some Monocotyledons. Ex. : Calamus. 



V. Radial, characterized by a number of xylem and phloem masses 

 alternating with one another. Seen in the roots of all Spermatophytes 

 and Pteridophytes. 



Xylem is that part of a fibrovascular bundle that contains wood 

 cells and fibres. It may also contain trachese, tracheids, seldom sieve 

 tubes. 



Phloem is that part of a fibrovascular bundle that contains sieve 

 tubes, phloem cells, and often bast fibres. 



Classification of Tissues According to Function. — According to 

 their particular function, tissues may be classified as follows : 



I. Conducting Tissue 



II. Protective Tissues 



Parenchyme (Fundamental tissue). 

 Xylem cells. 

 Tracheae (ducts). 

 Phloem cells. 

 Sieve tubes. 



Epidermis (outer cell walls cutinized) 

 Cork (suberized tissue). 



j Bast fibres. 

 III. Mechanical Tissues \ Wood fibres. 

 [ Stone cells. 



PLANT ORGANS AND ORGANISMS 



An organ is a part of an organism made up of several tissues and 

 capable of performing some special work. 



An organism is a living entity composed of different organs or parts 

 with functions which are separate, but mutually dependent, and es- 

 sential to the life of the individual. 



The organs of fiowering plants are either Vegetative or Reproduc- 

 tive. The vegetative organs of higher plants are plant hairs, roots, 

 STEMS, and leaves. They are concerned in the absorption and elabo- 

 ration of food materials either for tissue-building or storage. 



The reproductive organs of higher plants include those structures 

 whose function it is to continue the species, y\z., the flower, fruit and 

 seed. 



