84 A. H. Graves, 
1. As would be expected, no cortical leaf trace bundles are 
present. 
2. The central vascular area is very similar to that of the stem. 
The tracheae in the center are pretty well disorganized, which is 
natural when one calls to mind the considerable extension of the 
peduncle. 
3. The lacunae are more numerous and much larger in proportion 
to the diameter of the peduncle than in the stem (Text-fig. 9; Pl. VI, 
fig. 34). 
4. In comparison with the stem the epidermis has slightly thicker 
walls, and small intercellular spaces may occur between it and the 
subjacent layer, an appearance which one never sees in cross sections 
of the stem (Text-fig. 10). 
5. Occasionally some of the epidermal cells have a peculiar 
halved appearance, as if a periclinal wall divided an ordinary ep- 
idermal cell into two parts. This is due probably not to a division 
in the epidermal cell, but to the fact that a smal] subepidermal cell 
is wedged up close to a small epidermal cell (Text-fig. 10). 

Figure 10.—Portion of cross section of peduncle ; x, apparent- 
ly double epidermal cells ; /a, lacunae; 7, intercellular spaces. 
>< 300. 
On the whole, the main differences between this structure and 
that of the ordinary stem are its lack of cortical bundles and its 
lighter construction. The latter is explained when one recalls the 
fact that the peduncle for a great period of its existence floats, 
and hence its specific gravity must be small. 
