Cockayne. — Plants of Chatham Island. 289 



are growing side by side, which, so far as general appearance 

 goes, might be taken for three distinct species." 



Dracophyllum paludosum, like O. semidentata, when grow- 

 ing amongst L. traversii, is only leafy on those stems which 

 emerge from that latter plant. It often occupies much drier 

 ground than even 0. semidentata. When fully grown and 

 under the most favourable conditions it may be about 1-8 m. 

 in height, and is of rather a fastigiate habit." It has long 

 creeping woody underground stems, giving off numerous strong 

 cord-like roots. Seedling plants also show this rhizomatous 

 habit. This spreading of roots or underground stems near the 

 surface of the bog is a special characteristic of bog plants all 

 over the world, for in such a position it is possible to get the 

 supply of oxygen for these underground organs which is so 

 deficient in the deeper layers of the boggy peat. Professor 

 W. F. Ganong describes how he traced a stem of Rubus 

 chamcemorus in a New Brunswick peat bog for a distance of 

 17 ft. without finding an end (19, p. 142). The leaves of D. 

 paludosum are much like those of certain other New Zealand 

 Dracophyllums, being needle-shaped and stiff. They are 4 cm. 

 long by 1mm. broad, and have a short sheathing base. 

 Usually they are semivertical, but sometimes almost quite 

 vertical. The upper surface is slightly concave and the 

 under- surface convex ; both surfaces have a strong cuticle, 

 and possess stomata. The vascular bundles are surrounded 

 by stereome, which extends from one surface of the leaf to 

 the other, and alternates with the chlorenchyma. 



Originallv the Lepyrodia formation must have occupied 

 very large areas not only on the southern tableland, but on 

 other parts of the island, especially on the low-lying ground 

 in the north, where many relics of this formation still exist ; 

 such, for example, may be seen in abundance in the boggy 

 ground south of Wharekauri Hill. In another part of the 

 flat land of the north-west peninsula several acres which had 

 evidently once been this formation were covered with young 

 plants of Olearia semidentata. On these northern bogs 

 Cladium gunnii is often quite common. 



The xerophily of bog plants is a most astonishing pheno- 

 menon, and has received various explanations, none of which, 

 however, seem to me altogether satisfactory. The most 

 generally accepted at present is that of Schimper (48, p. 18), 

 which is thus stated by Dr. Cowles (14 2 , p. 145) : " Schimper 

 believes that these structures" — i.e., xerophytic structures — 



* Compare Kirk's remarks (42, p. 225) on D. scoparium, which, of 

 course, may be the same species as the Chatham Island plant : " It 

 is a compact plant of fastigiate conical habit of growth, exactly like that 

 of Cupressus semper vir ens, and quite unlike that of any other plant." 

 19 



