50 
Groom — On a New 
B. The Scape . 
The structure of other parts of the stem is in all essentials 
identical with that of the rhizome. Ascending the axis, the 
cells decrease in size and number. The outermost layer of 
the general sheath loses its likeness to the endodermis, and 
as the leaves decrease in number the vascular bundles 
naturally become fewer. 
Close under the flowers the axis is triangular in cross- 
section. The cortical layers are reduced to two or three in 
number. The general sheath is triangular also in the section, 
and two to three layers in thickness. Within the three angles 
of the sheath are three pairs of larger bundles, the bundles 
lying within the sides of the triangle being smaller. 
ill. The Leaf (Fig. 7). 
The leaves are more or less closely pressed against the 
axis. 
Each consists of a lower (outer) and an upper (inner) 
epidermis, with a certain amount of undifferentiated mesophyll 
in which runs the single vascular strand which enters the leaf. 
The epidermis consists of typical cells, and towards the 
margins its two layers compose the whole thickness of the 
leaf. Stomata occur only in the lower (outer) epidermis, and 
solely in that portion which covers the midrib. 
The mesophyll forms a sheath round the vascular strand 
in the midrib, and suddenly thins off towards each side. 
So that the greater part of the leaf consists simply of 
two layers of epidermis with here and there a single or 
double layer of mesophyll-cells. The walls of all the 
mesophyll-cells are thin but lignified, excepting in the 
immediate neighbourhood of the midrib, where the walls 
consist of cellulose. 
The cells in the outer (lower) half of the leaf in this region 
contain excreta, especially in the form of raphides enclosed in 
mucilage. The adjacent parts of the axis may be quite 
devoid of raphides. This recalls the same distribution in 
