281 
Festuca rubra near Cardiff. 
At the top of the sheath there is a slight overfolding of the 
tissue ; then the upper fold becomes free from the lower and the 
edges pass round into the ligule and lamina. 
The sheath is cylindrical for the greatest part of its length, 
but just previous to splitting a slight fold appears in it on the side 
opposite that from which the lamina passes off. The upper limb 
of this fold becomes free from the lower by the disappearance of 
the connecting plate of tissue and the sheath is now split, the free 
edges passing into the ligule and lamina. 
The ligule is merely a slight ridge or cushion of thin walled 
parenchyma. The cells of the outer surface grow out as short 
papillae or trichomes. 
The lamina is complicate (Fig. 11). Along the upper surface 
are five longitudinal ridges, clothed with minute hairs, which give 
a dull green appearance to the surface. The shape of transverse 
sections varies slightly in passing from ligule to tip. From Hackel’s 
description it would appear that he used herbarium material in 
which the softer tissues had shrunk, the resulting shape depending 
upon the position and amount of resistant tissues. The vascular 
bundles, five to seven in number, pursue a straight course from 
base to apex. At intervals branches pass out into the mesophyll. 
Each branch consists of a row of short, stout, spirally-thickened 
tracheides, connected at one end with the reticulate narrower 
elements of the main bundle, and ending either in contact with 
mesophyll cells or with an intercellular space. Each branch strand 
is surrounded by cells containing large nuclei and granular proto¬ 
plasm. These branch strands are more numerous in grandiflora. 
The sub-epidermal strands of sclerenchyma are larger in grandiflora 
than in tenuifolia : hence the somewhat greater rigidity of the lamina 
of the former. 
The lower (outer) epidermis in surface view consists of 
alternating long and short cells. The former are from six to 
fourteen times as long as broad and their long anticlinal walls are 
corrugated. The surface walls are furnished with the so-called 
marginal pits, which occupy the troughs of the undulations of the 
anticlinal walls on one side only, and extend obliquely upwards and 
outwards from the cell-cavity towards the surface (Fig. 12). The 
short cells in the neighbourhood of the ligule project beyond the 
general surface as hairs. The outer walls are strongly thickened, 
and the thickening extends to about midway along the anticlinal 
walls. 
