284 Transactions. — Botany. 



Bog Formations in General. 



A very large proportion of the tableland and a consider- 

 able part of the lowland, especially on the north-west 

 peninsula, consists of boggy ground. The vegetation of the 

 bogs has been burnt in some places again and again, in others 

 only occasionally, but in very few places indeed is it still in 

 its primeval condition. To tell whether a portion of vegeta- 

 tion is primitive or modified is not easy. Much of the plant- 

 covering, looking to all intents and purposes unmodified, 

 Mr. W. Jacobs assures me has been burnt at any rate once, 

 although that may have happened twenty years ago or more. 

 Phormium ienax, which certainly played a very conspicuous 

 part originally in the plant-covering of all places except the 

 very wettest, is now almost extinct, and the exclusion of so 

 large and characteristic a plant from a formation must have 

 led to far greater extension of others with which it formerly 

 shared the ground. The bog soil consists of peat, varying 

 considerably in its water-content, thus leading to several dis- 

 tinct combinations of plants, one combination giving place to 

 another according as the ground becomes drier, until, com- 

 mencing in the wettest part with a Sphagnum bog and pass- 

 ing through various shrubby stages, a " tableland forest " may 

 finally replace the bog. Below, the bog formations are 

 treated of in what I take to be their order of development, 

 beginning with the earliest, the Sphagnum bog, which for its 

 part would originate in a lake or low-lying ground covered 

 with water. 



Sphagnum Bog. 



At one time in the history of Chatham Island the Sphag- 

 num bogs must have been very extensive ; even when the 

 white man first arrived Sphagnum must have been much 

 more abundant than it is at present. Here and there on the 

 tableland primitive Sphagnum bogs may be encountered ; 

 others of considerable extent occur in other parts of the 

 island, of which one on the high ground between Whanga 

 marino and Te Whanga is of great interest, but most likely 

 even this is not by any means in its primitive condition. The 

 Sphagnum bogs of the tableland usually form small islands in 

 the midst of the second stage of bog, the Lepyrodia formation, 

 described in the next section. The Sphagmwi, perhaps an 

 undescribed species peculiar to Chatham Island, is extremely 

 wet, and, in the centre of the bog, pools of water lie on the 

 surface. Walking on the surface one sinks up to the ankles, 

 and in the centre of the bog much deeper still. Growing on 

 the Sphagnum, in the very wettest places, is a small quantity 

 of Isolepis sp. and Garex sp. Where the bog is a little drier 

 Hierocltloc redolens, Poa chathamica, and Pratia arenaria are 



