Pegg. — Ecological Study of New Zealand Sand-dime Plants. 161 



Inflorescence 4—9 in. long, clusters of spikelets spirally arranged around 

 the upper part of the stem, each cluster subtended by a linear bract like 

 the leaves, bracts about 2 ft. long, J in. broad, expanding at base around 

 the spikelets to about ^-f in. across. Spikelets densely crowded, brown or 

 reddish-brown. 



(c.) Leaf -anatomy. 



Epidermis : Cell-walls thick ; some four or five rows of cells above each 

 band of stereome, elongated, and with undulate cell-walls. About four rows 

 of cells alternating with the stereome. cell- walls not so undulate, more 

 irregular, and with stomata ; stomata sunken, arranged parallel with leaf- 

 axis ; cuticle thick, orange-coloured commonly. 



Chlorenchyma : A band extending from vascular bundles to epidermis, 

 except where interrupted by stereome. Continuous except for the presence 

 in the middle of the concave side of the leaf of large colourless polygonal 

 cells just beneath the epidermis and continuous with the central paren- 

 chymatous tissue. Outer layers of chlorenchyma consist of palisade cells, 

 compact. Towards the vascular bundles the chlorenchyma cells are more 

 rounded or polygonal, with intercellular spaces, thus forming a tissue like 

 spongy parenchyma ; air-spaces beneath stomata. 



Stereome strongly developed — (1) subepidermal, in bands regularlv 

 arranged parallel to leaf-axis, and alternating with groups of palisade cells ; 

 (2) with vascular bundles. In adult plant, stereome forms thick cords in 

 the central colourless parenchyma, adjacent to the bundles ; also a well- 

 developed sheath around each bundle. In the portion of this sheath nearest 

 the chlorenchyma plainly appear passage-strands, radiating from the central 

 cavity of the cells. As in Scirpus nodosus, peculiar processes appear from 

 the stereome into the epidermis. 



Fibro-vascular bundles are arranged in one or two rings just internal to 

 the chlorenchyma, with thick-walled sheaths enclosed in colourless paren- 

 chyma sheath. The stereome groups are developed adjacent to the vascular 

 bundles towards the convex surface, not to those on the concave. 



The chief points in which the adult plant differs from the seedling are 

 the development of stereome tissue, and the increased compactness of the 

 chlorenchyma. 



(d.) Conclusion. 



Scirpus frondosus, with its characteristics — tufted growth-form, rigid 

 arched leaf, thick cuticle, sunken stomata, compact chlorenchyma cells, and 

 strong development of stereome — is a typical xerophyte. Also, the well- 

 developed rhizomes, with their ability to strike upwards and root, save 

 the plant from being buried by wind-blown sand, and give to it its strong 

 sand-binding propensity. Thus Scirpus frondosus is, by both habit and 

 structure, well adapted to its environment. 



7. Carex pumila. . , TT 7 . 



(a.) Habitat. 



Found in moist sand hollows or plains commonly in northern portion of 

 the New Brighton beach. The plant acts as a minor sand-binder when a 

 hollow is invaded by sand. 



(b.) Growth-form. 



A small sedge, 1 ft. or less in height, with leaves arching over towards 

 the ground. 



6 — Trans. 



