no 
PHARMACEUTICAL BOTANY 
usually resembles the other parenchyma layers of cortex as to struc¬ 
tural characteristics, save that it frequently contains more starch. 
In fern stems, roots of Monocotyledons and of Dicotyledons of 
primary growth, however, its cells are clearly distinguished from the 
other cells of the primary cortex by their elongated form and sub- 
erized (occasionally lignified) radial walls. In the roots of Mexican 
Sarsaparilla the inner as well as the radial walls are suberized; in 
those of the Honduras variety, inner, radial and outer walls all show 
suberization. Endodermal tissue is devoid of intercellular-air-spaces. 
Its cells contain protoplasm and nucleus. Its functions seem to be 
to give protection to the stele (tissues within it) and to reduce per¬ 
meability between primary cortex and stele. 
CORK 
Cork or suberous tissue is composed of cells of tabular shape, 
whose walls possess suberized layers. Its cells are mostly filled 
with air containing a yellow or brownish substance. It is derived 
from the phellogen or cork cambium which cuts off cork cells out¬ 
wardly. Cork tissue is devoid of intercellular-air-spaces. It 
forms a protective covering to the roots of secondary growth, stems 
(after the first season) of Dicotyledons and Gymnosperms, and 
wounds of stems and branches. Living cork cells contain protoplasm 
and cell sap while dead cork cells are filled with air. 
The walls of cork cells resist the action of concentrated sulphuric 
acid. They are colored green, when in contact with alcoholic 
extract of chlorophyll for several days in the dark. 
LATICIFEROUS TISSUE 
This form of tissue comprises either latex cells , laticiferous vessels, 
or secretory cells differing from each other in origin and method of 
development. Latex cells are elongated tubes which take their 
origin from meristematic cells of the embryo. Elongating with the 
growth of the plant, they branch in various directions and traverse 
at maturity all of its organs. Such cells are abundant in the 
following families: Apcoynacece, Asclepiadacece, Urticacece and 
Euphorbiacece. 
