BRAKE, OR BRACKEN 95 



full-grown fronds then consisting merely of a series of 

 pairs of branches from bottom to top. The unrolling 

 of the young fronds is very curious, and well worthy of 

 watchful notice. 



The bipinnate branches, or pinnae, are in general 

 ovate slightly elongated, their pinnae (the secondary 

 pinnae) narrowly lanceolate. These last are placed 

 rather closely together, and again divided into a series 

 of pinnules, which are either undivided and attached 

 to the rachis by their stalkless base with a line of 

 spore-cases along each margin, or become larger and 

 then more elongated and deeply pinnatifid with the 

 lines of spore-cases on the margins of the lobes. The 

 apexes of the primary and secondary pinnae and the 

 pinnatifid pinnules become less and less divided, until 

 at last they end in a single lobe more or less elongate. 

 The venation is very various, depending on these 

 differences of development. Each pinnule has a dis- 

 tinct midvein, producing alternate lateral veins, which 

 become twice forked and extend to the margin, where 

 they meet a longitudinal marginal vein, which forms 

 the receptacle. The indusium consists of a bleached 

 membranous, fringed expansion of the upper skin of 

 the fronds, which turns back so as to cover the spore- 

 cases ; but there is here another membrane lying 

 under the spore-cases, no doubt a similar expansion of 

 the skin of the under-surface. The fronds are annual, 

 but owing to their rigid texture do not easily die off 

 altogether, only losing their summer verdure, standing 

 often through the winter, or until bowed bv the 

 weight of snow, in all their summer glory of form, and 



