Feb. 1, 1925 
Vegetative Organs of Sugar Cane 
203 
THE STEM 
A node and an internode taken from 
the upper third of a large cane was 
used as representative material for the 
anatomical study of the stem. The 
internode was uniform, about cm. 
thick and 15 cm. long; the node was 
slightly thinner and exhibited regions 
of internal and external structural dif¬ 
ferences and will, therefore, in this 
discussion be subdivided into: (a) The 
node proper, which is limited above 
by the insertion of the leaf sheath; 
(6) the Keimring, which contains a 
bud and several rows of root primordia; 
(c) the intercalary meristem from which 
elongation of the internode takes place. 
These regions differ from each other, 
but because of the transition zones, 
however narrow, they will be treated 
in sequence rather than as altogether 
different entities. 
A cross section of the internode (pi. 
2) shows numerous vascular bundles 
embedded in parenchymatous tissue. 
Externally it is limited by a thick 
epidermis which,, for further protec¬ 
tion, is covered by a layer of wax. 
The vascular bundles are not arranged 
in a simple ring, but lie scattered 
throughout the section. Their num¬ 
ber increases from the center toward 
the periphery, whereas their size grad¬ 
ually decreases. At the periphery the 
bundles are so small and so close 
together that they form practically a 
solid ring. The vascular tissue.is sepa 1 - 
rated from the epidermis by a cortex 
which varies in width and composi¬ 
tion with different regions of the stem. 
The parenchyma constitutes, the 
filler between the bundles, except in 
the peripheral region, where it forms 
an uninterrupted layer comparable to 
the cortex of dicotyledonous plants. 
The parenchyma cells are thin-walled 
and separated by small intercellular 
spaces. In cross section the cells are 
roundish or somewhat elliptical, where¬ 
as vertically they have the form of 
short cylinders with straight or some¬ 
times rounded ends. The depth of 
the cells varies with their position in 
the stem, those in the internode being 
elongated near the vascular bundles, 
but in the nodes the cells are very short 
regardless of their radial position. 
The cortex forms a narrow band of 
tissue except in the Keimring where 
its width more than doubles. The 
two to four rows of cells next to the 
epidermis are small, thick-walled and 
lignified (pi. 15, A, and fig. 2). The 
vertical continuity of this sclerenchy- 
matous mantel, however, is broken by 
the occasional interpolation of paren¬ 
chymatous cells which abut externally 
on a stomate of the epidermis. This 
layer is followed, by several rows of 
thin-walled parenchyma, the cells of 
which remain cellulose even, in old and 
woody stems. There is a gradual 
transition from the cells of the cortex 
to those of the bundle parenchyma. 
The cells of this transition zone, which 
form the filler between the peripheral 
bundles, grow progressively -larger 
centripetally and the walls become 
lignified wholly or in part. In the 
region of the Keimring the cortex is 
composed of uniformly small cells which 
remain cellulose. In very old stems, 
however, the two hypodermal layers 
may show partial lignification. 
Epidermis op the stem. —An epi¬ 
dermis typically forms a single layer of 
cells, possesses stomates and produces 
outgrowths in the form of hairs. In the 
stem of the sugar cane, however, while 
stomates are sparingly developed, hairs 
are entirely wanting, though in a differ¬ 
ent variety they have been reported 
once by Soltwedel (11, p. 28). 
The individual cells of the epidermis 
vary in size and form; on the whole, 
however, they are remarkably uniform. 
There are present two distinct types of 
cells alternating with one another; 
elongated rectangular cells with undu¬ 
lating walls, and short cells which occur, 
singly or in pairs (pi. 5, C). 
The long cells form four-sided prisms 
with a mean radial diameter of 9.8/i and 
a length varying between 54 and 184/i. 
The outer walls are greatly thickened 
and cuticularized. There is also pres¬ 
ent, especially in the region below the 
insertion of the leaf sheath, a wax de¬ 
posit composed of a layer of densely 
crowded wax particles in the form of 
hooked rods (fig. 2). The walls of the 
epidermis are pierced by numerous pits, 
which are easily seen when the section 
is treated with chloral hydrate or some 
suitable clearing agent. In the region 
of the intercalary meristem the epi¬ 
dermal cells are very broad, and the 
walls less tortuous and comparatively 
thin (pi. 5, A). 
The short cells are transversely rec¬ 
tangular, but the two components of 
the pair are rarely uniform. One is 
usually smaller, narrower tangentially 
and has silicified walls. The larger of 
the two has a tendency to be irregular; 
it is frequently pointed, which gives it 
the appearance of a wedge. Occa¬ 
sionally one or even both of the short 
cells are wanting, which results' in 
the latter case in a continuous longi¬ 
tudinal row of long cells. 
Central, stem bundles. —In order 
to fully appreciate the different aspects 
