360 Transactions. 



the hill-crests, anc] liere Marrubium has become the worst pest of the dis- 

 trict. It remains to be seen whether with time it will work itself out. 

 Probably in the absence of sheej) it is but littlt> distributed. Cattle also, as 

 is well known, rapidly destroy the undergrowth in bush country. Rabbits, 

 also, oir the area dealt with are ])robably almost entirely destructive in 

 their action. They reach many places which are either inaccessible to sheep 

 or at least not usually grazed by them. On some of the rockv points of 

 the Lyttelton Hills, whicji would otherwise be plant-sanctuaries, scarcely a 

 plant is left untouched by them. Shrubs and grasses are all grazed, and 

 only the inaccessible chasmophytes escape. Hares apparently are much 

 less destructive than rabbits, because they are in smaller numbers, do not 

 burrow, and do not frequent cliffs and rocks. The tendencv of these 

 agents is not o]ily to reduce the number of indigenous species, but also, as 

 a rule, to limit the numbers of the individuals in the remaining specie'^. 



Certain species, however, are apparently on the increase as the result of 

 changed conditions. Such are Danthonia pilosa, D. semiannularis, Acaena 

 novae-zelandiae, Coriaria sarmentosa, Cotula squalida, Dicho)if]r(( hrevisepala, 

 and Oxalis corniculatii. The two last-mentioned invade even cultivated 

 ground, and 1 have seen 0. conn'culata growing about the steps of the public 

 buildings of Christchurch. 



During a succession of dry seasons the grasses mentioned become common 

 in garden lawns on the hills, and replace temporarily or permanentlv the 

 shallow-rooted lawn-grasses. In dry seasons, too, rabbits attack the bark 

 of trees, and thus assist the drought in its attack upon the vegetation. 

 Melicytus ramiflorus, Schefflera digit at a, and Nothopanax arboreum are 

 amongst the first to suffer, particularly when standing in the o]ien. 



The Plant Associations. 



Further discussion of such changes may be postponed for tlie present, 

 and taken when we come to consider shortly the chief of the indigenous 

 plant societies. They may be roughly classified as follows : — 



(1.) Salt marsh 



(2.) Salt meadow 



(3.) Coastal rocks !• Coastal. 



(4. Sand-dunes 



(5.) Coastal scriib ' 



(6.) Tussock-grasslands. 



(7.) Inland clift" and rock. 



(8.) Forest. 



(9.) Lowland scrub and heath. 



(10.) Subalpine scrub. 



(11.) Subalpine grasslands. 



(1) (2) The Salt Marsh aii<l the Salt Meadow. 



These are developed at the head of the tidal flats, and are well seen 

 at Teddington in Lyttelton Harbour, also on the Sumner Estuary and in 

 a few other places on the peninsula. At Lake Ellesmere there are vast 

 extents of brackish marsh and meadow ; but these scarcely come within 

 the scope of this |)aper. Though some of the species occurring in the por- 

 tion of the lake adjacent to Kaituna have been listed, no attempt has 

 been made to exjilore the lake and its borders as a whole. It would 

 undoubtedly form an interesting field for the botanist, and one as yet 



