Feb. 1, 1925 
Vegetative Organs of Sugar Cane 
199 
various types. These are most numer¬ 
ous at the two joints and along the 
median axis. At the base of the ligule, 
but arising from the inner epidermis of 
the sheath, are long silky cilia. 
The blade is linear lanceolate, up to 
two meters long, and at the middle is 
from 5 to 7 cm. wide. There is a 
prominent midrib which projects from 
the lower surface and forms a groove in 
the upper. The leaf margin is denti¬ 
culate with fine silicified teeth. The 
surface varies from hispid to pubescent 
with the longer, softer types of hair 
occurring on the lower surface. 
The color of the cane is characteristic 
of the variety. Gradations, however, 
are induced by light and the age of the 
organ. The sheath is of a uniform 
green, which becomes pale toward the 
margins. Sometimes the basal part of 
the young organ shows a different color, 
a reddish or purplish tinge, which, 
however, disappears as the plant 
matures. The upper surface of the 
blade is a bright green, while the lower 
tends to take on a grayish tinge owing 
to the presence of hairs. 
The root system of the cane, like 
that of other grasses, is composed of 
numerous fibrous roots. A distinct 
taproot is found only in seedlings and 
even here it is poorly developed, ceasing 
to grow after a brief period. The 
secondary lateral rootlets are much 
thinner than the primary ones and have 
but an ephemeral existence. When 
they become detached from the larger 
roots they leave abscission zones which 
may serve as infection courts for num¬ 
erous parasites which, as is well known, 
invade the root system of the cane more 
readily than that of other plants. 
The inflorescence forms a large open 
panicle. The flowers are arranged in 
small spikelets, each surrounded at the 
base by a tuft of silky hairs from two to 
three times the length of the spikelets. 
The latter are grouped in pairs: one 
sessile, the other pedicelled. Both 
spikelets are perfect and awnless. 
Each flower is subtended by two bracts 
which form the outer and the inner 
glumes. The outer glume is mem¬ 
branaceous, pointed, entire-margined 
and two-nerved. The inner glume is 
similar, but possesses a median keel. 
Continuing the two-ranked arrange¬ 
ment of the two glumes is the sterile 
lemma which is lanceolate, pointed, and 
practically without veins. The fertile 
lemma and palet of the typical grass 
flower are wanting. At the base of the 
flower, just inside the inner glume, are 
two thick, hyaline lodicules. These 
two lodicules and a small scale just 
inside of and inclosed by the sterile 
lemma may be considered the tri- 
merous perianth of the flower. Lastly, 
the axis bears a whorl of three stamens 
and the ovary. The stamens have 
two-celled, versatile anthers, each sus¬ 
pended by a delicate filament. The 
ovary is short-stalked, erect, one- 
celled, and contains one ascending 
anatropous ovule. Owing to infertile 
or degenerate pollen in the Louisiana 
Purple variety, viable seeds are born 
only when foreign pollen is introduced. 
The fruit is small, about 1^2 mm. 
long with a distinct constriction in the 
region opposite the embryo. It is 
indehiscent and included in the glumes 
and the sterile lemma. The pericarp 
is thin and intimately united with the 
testa. The comparatively large em¬ 
bryo lies in contact with the starchy 
endosperm by means of the cotyledon, 
which acts as an absorbing organ. 
The sugar cane grows acropetally 
by a cone-shaped growing point. The 
increase in length of the stem, however, 
is due to an intercalary meristem at 
the base of each internode. The leaves 
are cut off by the apical growing point 
in rapid succession, and as new leaves 
appear a bud is formed in the axils of 
the older ones. The leaves grow much 
more rapidly than the stem, as can 
easily be seen in secondary shoots 
which have leaves several feet long, 
while the growing point is still under¬ 
ground. The formation of successive 
leaves and the subsequent growth in 
the intercalary zone divides the stem 
into segments, each consisting of a node 
and an internode. After the plant has 
reached a certain size, the lower under¬ 
ground buds initiate development and 
form secondary shoots, the amplifica¬ 
tion of this process resulting in stools 
which may contain scores or even 
hundreds of stalks. 
ANATOMY 
The material for study was grown 
in greenhouses at the Arlington Experi¬ 
ment Farm, Rosslyn, Va. The green¬ 
houses had been especially constructed 
for the growing of sugar cane, in order 
to insure the most natural development 
of the plants. 
The material taken from the green¬ 
house was studied while fresh and many 
of the photographs were obtained from 
free-hand sections of fresh material. 
For the purpose of securing permanent 
records, representative material was 
killed in Flemming’s stronger solution, 
embedded, some in paraffin, some in 
celloidin, sectioned, and stained in the 
usual manner. 
