158 Transactions. 



4. Festuca littoralis. . , TJ , . 



(a.) Habitat. 



Found commonly all along the dunes, sometimes on the foredune among 

 Scirpus frondosus, and rarely, even on the shore, in front of the foredune, 

 where, so far as New Brighton is concerned, the only other vegetation is 

 the introduced succulent cruciferous plant Cakile maritima. 



(b.) Growth- form. 



Forms close-growing yellowish-green tussocks, usually 2-3 ft. high, and 

 measuring about 5 in. through at the base ; several small tussocks com- 

 monly grow together, so that the whole clump measures more than 1 ft. 

 through at the base. Very like Poa caespitosa, but can easily be distin- 

 guished by the inflorescence. 



Roots many, long, spreading, covered with rootlets. 



Leaves narrow, strongly involute, appearing almost cylindrical, ending 

 in a point, smooth, shining, pale green or yellowish. 



Inflorescence a panicle, long, dense, narrow, spike-like, with broad spike- 

 lets. 



(c.) Leaf-anatomy. 



Leaf-margins almost meeting above the midrib, and hence only one 

 surface exposed. From the slight opening between the margins to the mid- 

 rib extends a narrow fissure, with lateral furrows between the veins, reaching 

 two-thirds of the way to the exposed surface of the leaf. The ridges above 

 the vascular bundles between these furrows are broad and rounded. 



Epidermis : Inrolled surface — 'Cell- walls undulate, cells elongated, many 

 cells smaller but extended into straight or curved spreading unicellular 

 hairs which line the main cavity and lateral furrows with a dense cross- 

 work ; stomata numerous in the furrows, clefts in direction of leaf-axis, 

 subsidiary cells present. Exposed surface — long rectangular cells alter- 

 nating with short cells ; cell-walls more undulating than on the other sur- 

 face ; no stomata ; waved cuticle. 



Hypodermis present beneath epidermis of exposed surface, consisting of 

 one or two layers of small thick-walled cells, merging gradually into the 

 thick- walled colourless parenchyma which surrounds the mestome bundles, 

 separates the chlorenchyma from the exposed surface, and extends right 

 along the ridges from one surface of the leaf to the other. 



Chlorenchyma : Relatively small patches lining the ends of the furrows 

 in horse-shoe form, and in bands lying at the sides of the ridges ; cells small, 

 irregularly polygonal, thin-walled. 



Mestome bundles of typical monocotyledon structure, with parenchyma 

 sheath, and mestome sheath with inner walls much thickened ; one bundle 

 in the middle of each ridge. 



(d.) Conclusion. 



The presence of the following characters shows that Festuca littoralis is 

 strongly xerophytic : Tussock growth-form, leaf strongly involute, inner 

 surface furrowed, with hairs, stomata in furrows, strong reduction of chloren- 

 chyma and development of colourless thick-walled parenchyma, which may 

 be considered a water-tissue. 



Two points of difference from Poa caespitosa are interesting — namely, 

 absence of stereome, which is compensated for by the thick walls of the 

 colourless parenchyma ; and thinner walls of chlorenchyma. 



