PLANT TISSUES 
69 
PARENCHYMA 
Parenchyma or Fundamental Tissue is the soft tissue of plants 
consisting of cells about equal in length, breadth and thickness 
(isodiametric) with thin cellulose cell walls enclosing protoplasm and 
a nucleus and frequently substances of a non-protoplasmic nature. 
There are four generally recognized types of parenchyma, viz. : 
O rd inary Parenchyma (S of t Groun d Tissue , F undamen tal Tissue ) . 
— Next to the meristem this is the least modified of all plant tissues. 
It is composed of thin-walled cells, commonly polyhedral or sphe- 
roidal in form and often of approximately the same length, breadth, 
and thickness (isodiametric), the cell walls are composed of cellu- 
lose which is usually unmodified. Protoplasm and a nucleus are 
always present, but in old cells are only seen as a thin layer pushed 
up against the cell wall. Ordinary Parenchyma may be seen 
composing the soft tissues of roots, stems, and barks. 
Assimilation Parenchyma (Chlorophyll or Chromophyll Paren- 
chyma, Chlorenchyma).— This form of parenchyma tissue is found 
in foliage leaves, floral leaves, in the outer region of young green 
stems and fruits. Its cells are thin walled and vary in shape from 
more or less isodiametric to irregular and elongated forms. The 
cells always contain chloroplasts or plastids in whose pores may be 
found some other coloring substance. 
Conducting Parenchyma. — This type of parenchyma functions 
in the rapid translocation of food materials to distant regions in the 
plant. It includes the wood parenchyma cells of the xylem which 
convey a portion of the crude sap (water with mineral salts in 
solution) and the phloem parenchyma (soft bast) which transports 
the elaborated sap (carbohydrate and proteid material in solution). 
Conducting parenchyma cells differ from those of ordinary paren- 
chyma in being usually more elongated and in conducting soluble 
food materials with greater celerity. 
Reserve Parenchyma. — This resembles ordinary parenchyma in 
many particulars of structure but differs from it mainly by its cells 
being filled with starch, protein crystals, or oil globules. It is 
usually found in seeds, fleshy roots, or underground stems such as 
tubers, corms, and bulbs. 
