VI ARUNDINARIA SIMONI 61 
as many as twelve) and of equal size. At the very top of 
the culm, however, the last four or five blades have a distinct 
midrib and assume the character of true leaves. Both the 
sheath and the blade are in a green state tessellated, but this 
tessellation disappears when the parts wither. Under the 
lens the sheath is seen to be covered with a thick silvery 
white down, which acts as a waterproof coat protecting the 
stomata. Between the sheath and the stem, as a further pro- 
vision against the attacks of water, is secreted a thick coating 
of white waxy bloom, which may be scraped off with the finger- 
nail. It is found in the greatest profusion immediately 
under the projecting nodes, and diminishes in quantity until 
within about 1 inch or 14 inch of the top of the node, below 
which it almost disappears, being formed again under the 
next rim. The lower part of the internode being entirely 
encircled and guarded by the sheath does not stand in need 
of this protection of the transpiratory organs against moisture ;' 
but as the culm is drawn up, the sheath, narrowing away to 
the ligule, leaves the upper part of each internode uncovered, 
while in the meantime the waxy secretion has been formed 
and so the bared portion of the stem has a sufficient protector. 
When the sheath finally falls off, the whole of the internode 
is found to be finely powdered with a delicate bloom. 
The limbus, or blade, soon breaks away from the sheath 
and disappears, but the ligule remains with the sheath, falling 
and dying with it. The lower and upper joints of the culm 
are far shorter than those in the middle, where they reach 
their maximum. 
When the culm has reached its full height branching 
! Vide supra, p. 45. 
