160 Transactions. 



leaf, but there is maximum lighting for the vegetation as a whole, since the 

 more vertical the leaves the more numerous may they be in any given space, 

 and yet have sufficient light to live." And on page 666, on the subject of 

 plants such as the rushes (Juncus and Scirpus), " It has been suggested that 

 their exposure to intense light, reflected as well as direct, makes verticality 

 almost as advantageous as in xerophytic habitats. It. is much more likely 

 that in rushes, as in swamp-grasses and in flags, verticality is advantageous 

 because it permits a maximum display to light where growth is intense. 

 Whatever may be the causes or advantages, it certainly is striking that 

 leafless stems with a relative maximum of stem synthesis occur in such 

 opposite habitats as deserts and swamps, and that the vertical habit which 

 means minimum light-exposure and maximum protection for the desert 

 individual means maximum light -expo sure for the mass of vegetation in 

 the swamp." 



In the case of the various sand-dune species which exhibit the tussock 

 form — e.g., Scirpus nodosus, Festuca littoralis — it seems that because (1) the 

 tussocks are commonly not closely packed together, and (2) the habitat is 

 xerophytic, the advantage of the tussock form is one of protection against 

 light -expo sure and excessive transpiration. At the same time, with such 

 a plant of Leptocarpus sim,plex, which grows in habitats varying from the 

 dune to the swamp, it may be that the advantage of the tussock form and 

 vertical leafless stem may be minimum light-exposure and maximum pro- 

 tection for the individual growing on dry sand, or maximum light-exposure 

 for the mass of vegetation in the swamp. 



6. Scirpus frondosus. , , TT 7 . 



(a.) Habitat. 



Scirpus frondosus is the most common of all plants on the sand-dunes 

 at New Brighton. It covers both natural and artificial foredune, sharing 

 its position on the artificial dune with the introduced marram-grass (Ammo- 

 phila arenaria). Towards the Sumner end of the beach Scirpus frondosus 

 reigns in almost undisputed sway on the foredune, the only other plant 

 growing there being Festuca littoralis, with the introduced Cakile maritima 

 on the shore close by. At the extreme end of the New Brighton beach, by 

 the Sumner Estuary, opposite the Shag Rock, Scirpus frondosus is extremely 

 common, giving to the dunes a very picturesque appearance by its orange- 

 red colouring. 



(b.) Growth-form. 



A sedge, with leaves thickly arranged resembling tussocks, propagated 

 enormously by means of its long thick rhizome ; green, brownish, or orange 

 in colour, giving a characteristic orange-brown colour to the vegetation. 



Rhizome thick, stout, sometimes an inch in diameter, woody, fibrous 

 (therefore hard to cut or break), long, creeping, often many yards in length 

 covered with old brown leaf-sheaths ; at frequent intervals giving rise to 

 stems with tufts of numerous leaves. 



Leaves numerous, closely packed, spreading, harsh, stiff, flexible, cori- 

 aceous, 1 \-2 ft. long, £— ^ in. broad, narrowing to long trigonous points;, 

 upper surface concave, under convex ; margins have small sharp teeth, and 

 there are one or two rows of teeth on the convex imder-surface. Young 

 leaves green with orange or brown colouring towards the tips, bases yellow 

 or yellowish-green, older leaves often orange or orange-red for the greater 

 part of their length. Leaf at base broadens out into a sheath, brown, mem- 

 branous, 3-4 in. long, about l|-2 in. broad at extreme base. 



