The Morphology of Riippia 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 VII, 

 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. PL III, fig. 8 and PL VII, fig. 43, 

 vsl show a transverse section, and PL 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, 

 f s I) and its base is coincident with the base of the floral axis for 

 nearly one half of its circumference. Its development can be easily 

 traced in PL IX, figs. 54, 55, 56, 51 and PL VII, Fig. 41, fsl, 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.^ 

 (PL VII, fig. 41,/5/). 



^ I have been unable to find a flower bud in wbich there was no branch, 

 in the axil of the upper subfloral leaf, which would of course, be an 



