The Morphology of Ruppia Maritima. 99 
In accordance with the Bonn Textbook I have adopted the term 
scale leaf; the leaf at the base of the ordinary branch will be referred 
to as the vegetative scale leaf, while that at the base of the ped- 
uncle will be termed the floral scale leaf. 
1. The Vegetative Scale Leaf. 
a. General Characters. 
This envelops the base of all axillary structures, except that in 
the axil of the upper subfloral leaf, and is developed on the side 
of the axillary member opposite to that of the subtending leaf. 
Flattened out, it is in the form of a long narrow triangle (Pl. VU, 
fig. 40), from 6 to 13 mm. in length; in position, its edges slightly 
overlap at the base, on the side nearest the subtending leaf 
(Text-figs. 19-20). If the axillary members are young, it completely 
envelops them; when they grow out, forming a branch, it remains 
sheathing the base of the branch. 
b. Internal Structure. 
Anatomically the vegetative scale leaf is composed of two layers 
of elongated large-vacuolate cells, rectangular in outline, with the 
nucleus flattened against the wall, and with a very few small chloro- 
plasts. No vascular bundles are present. PI. Ill, fig. 8 and Pl. VU, fig.43, 
vs/ show a transverse section, and PI. VII, fig. 37 a surface view. 
2. The Floral Scale Leaf. 
a. General Characters and Structure. 
The other form of scale leaf, which I have termed the floral 
scale leaf, occurs always at the base of the peduncle, on the side to 
ward the youngest or upper subfloral leaf (pp. 97-98 and Text-fig. 20, 
fs?) and its base is coincident with the base of the Horal axis for 
nearly one half of its circumference. Its development can be easily 
maeed in Pi EX, fies; -54, 55,.56, 51 and Pl. VIL, Fig. 41, js 2_and 
it will be seen that never at any time does it completely envelop 
the floral axis, as does the scale leaf the base of the axillary shoot, 
but nevertheless partly surrounds it. When the peduncle elongates 
in the course of floral development, the floral scale leaf remains at 
its base, similarly as in the case of the vegetative scale leaf. 
Moreover, in its growth this scale leaf follows the growth of the 
flower and is entirely in independence of the adjacent axillary bud.* 
fel Vil, fig 41, fs 7). 
17 have been unable to find a flower bud in which there was no branch 
in the axil of the upper subfloral leaf, which would of course, be an 
