Cockayne. — Plants of Chatham Island. 287 



liverworts and mosses, especially with Sphagnum, a relic of 

 the parent Sphagnum formation. In places where the three 

 dominant plants are growing more thinly still, and the under- 

 lying Sphagnum is exposed to the light, seedlings of Olearia 

 and Dracophyllum occur ; also Drosera hinata and Gentiaua 

 umbellata make their appearance, but these two latter are by 

 no means numerous. 



In some places the original Sphagnum is still quite thick ; 

 there the shrubbv growth becomes at once much reduced, 

 and its height quite one-half less. In such a place the sun- 

 light can have some effect, and in consequence more plants 

 appear. For instance, Corysanthes macrantha and Gar ex sp. ; 

 while Gentiana, Drosera, and Utricularia occur in greater 

 numbers. 



Here and there through the formation are a few stunted 

 plants of Phormium tenax which have strayed from the drier 

 ground, but which certainly do not really belong to this 

 formation. The most important constituents of this forma- 

 tion are Lepyrodia traversii, Olearia semidentata, and Draco- 

 phyllum paludosum. Of these Lepyrodia traversii, a strongly 

 marked xerophyte — as, indeed, are the other dominant plants 

 — occurs only in very wet bogs, and a slight diminution in 

 the wetness of the ground will cause it to disappear. It is 

 furnished with a strong rhizome 3 cm. in diameter, which 

 creeps through the Sphagnum or the peaty ground at a depth 

 of 5 cm. Prom this rhizome upright rush-like shoots are 

 given off at intervals, each bare for the lower third of its 

 length, but above branching laterally. These upper branches 

 are terete, dull-brown in colour, very smooth, stiff but quite 

 flexible, and about 1mm. to 1*5 mm. in diameter. These 

 stems function as leaves, and are provided with a dense 

 palisade parenchyma. A transverse section shows an irre- 

 gular-shaped lacuna in the centre of the stem, surrounded by 

 a large-celled parenchyma. This, again, is enclosed in a 

 ring of stereome, and round the periphery is a one-layered 

 epidermis with a very thick cuticle. The strong rhizome is 

 of great importance to the plant in assisting it to spread, 

 and in so preventing the advent of other plants. Whether 

 L. traversii is able to grow on dry ground like its relative 

 Leptocarpus simplex only experimental culture will prove, 

 though its structure should certainly fit it for very dry sta- 

 tions. Mr. Cheeseman, who first pointed out that L. traversii 

 occurred in New Zealand as well as the Chatham Islands, 

 where it was thought to be endemic, thus writes (4, p. 325) : 

 "In the Ohaupo locality Sporadanthus " — the genus under 

 which the plant was then placed — " is seldom found near the 

 margin of the swamp ; but towards the centre, where there is a 

 great depth of peat, which affords ample room for its creeping 



