44 2 Kashyap . — Notes on Equisetum debile , Roxb. 
distinctive characters gradually disappear and the endodermal cells can no 
longer be distinguished from the neighbouring parenchymatous cells. 
In the region of the hypocotyl in the young plant the changes in the 
form of the endodermis are as follows : The root is usually triarch without 
pith and with an external endodermis having suberized bands on radial 
walls. Higher up some parenchymatous pith appears in the centre and 
phloem comes to lie all round the xylem ring, as seen in a transverse section, 
and has a surrounding endodermis. At this stage a small bundle is given 
off for a branch, leaving a gap in the stele. A little higher the gap is closed. 
Then the three leaf-traces are given off for the first three leaves and the 
main stele also becomes separated into a few bundles (usually three). External 
endodermis here cannot be made out, though it becomes distinct a little 
higher up on the outside of the bundles only, but a little later it becomes 
continuous. At this place the internal endodermis appears as a small ring 
surrounding sometimes a single cell, or may be represented by a single cell 
with all its walls having suberized bands. Gradually the internal ring 
becomes wider and both layers persist up to the growing point. Thus, in 
the hypocotyl the internal endodermis forms an inverted cone, gradually 
