156 Transactions. 



(d.) Conclusion. 



Contrary to what might be expected from the fact that this plant fre- 

 quently grows in an exposed position on the active dunes, leaf-anatomy 

 shows structure far from xerophytic. There is a small amount of stereome 

 and of water-parenchyma, the epidermal walls are thick, but otherwise the 

 leaf is mesophytic. It is flat and green and thin, and the frequent stomata 

 are not well protected. 



Calamagrostis also grows in dune-hollows, where xerophytic characters 

 are not so necessary, owing to the greater amount of moisture and pro- 

 tection from winds. 



2. Arundo conspicua. . 



(a.) Habitat. 



Rarely occurs on the southern portion of the New Brighton beach — i.e., 

 between the pier and the Sumner Estuary ; more common on the north 

 beach, towards Belfast, where it is found some distance inland, where the 

 dunes are comparatively stable. Elsewhere a denizen of both swamp and 

 heath ; therefore a plant of very different stations, though a swamp may 

 be xerophytic. 



(6.) Growth- form. 



A very conspicuous grass, tall, often reaching a height of as much as 

 11 ft. ; forms large dense tussocks; inflorescences characteristic. 



Leaves long, relatively narrow, coriaceous, flat or involute, veins plainly 

 seen, ridged and furrowed. 



Inflorescence a showy panicle, yellowish-white, silky, 1-2 ft. long, thickly 

 branched, spikelets very numerous. 



Rhizome stout ; can grow upwards to some extent as buried. 



(c.) Leaf-anatomy . 



Epidermis : On exposed surface, a cuticle ; regular rectangular cells, 

 elongated in direction of the leaf-axis, alternating with small cells ; cell- 

 walls thick, wavy ; a few stomata. On inrolled surface, cells elongated, 

 cell-walls thin, stomata numerous in the furrows, subsidiary cells present, 

 epidermal cells commonly rounded, and with outer walls much thickened. 



Chlorenchyma in bands alternating with vascular bundles, reaching to 

 both surfaces of the leaf ; water-parenchyma in the midst of each chloren- 

 chyma band. Cells more or less polygonal ; air-spaces beneath stomata. 



Stereome present in subepidermal patches, sometimes extending from the 

 surface to the vascular bundles. The stereome immediately beneath the 

 epidermis consists of much smaller cells than that adjacent to the bundles. 



Fibro-vascular bundles, together with stereome, separate bands of chlo- 

 renchyma ; of typical monocotyledon structure ; sheath with thickened 

 inner walls, surrounded by parenchyma sheath. 



(d.) Conclusion. 



Arundo conspicua shows marked xerophytic characters — viz., inrolled 

 leaf, stomata in furrows and mostly on protected side of the leaf, water- 

 parenchyma, and stereome. The growth -form, the tussock, also is xero- 

 phytic. Its tall habit in all positions obviously exposes it to the full force 

 of the wind. On the other hand, its tussock form shelters the inner leaves, 

 and combats transpiration. 



