(6) The Tussock-grasslands.

These were originally found only where the hills were directly exposed to the action of the drying north-west wind, or where they were sheltered from the moist easterlies but met the full strength of the cold south-wester. The easterly winds—the prevailing winds of the peninsula—are much less arid than the north-wester, and less violent and cold than the south-wester; so they have interfered but little with forest growth. On the other hand, the area of exposure to the north-wester is well defined by the tussock belts of the north-western faces of the peninsula. The examination of such a point as Adderley Head well illustrates this contention. The tussock on the Lyttelton side is often withered, while the herbage on the Port Levy side is quite green; the rainfall on both sides must be the same. Wakaroa Head, the eastern point of Pigeon Bay, equally well if not better proves the same point. Here, no doubt, the rainfall is somewhat higher than at Lyttelton Heads, so that it is well above the minimum required for forest-production; yet the forest extended along the eastern side of Pigeon Bay only so far as it was sheltered from the direct action of the north-west wind. The projecting end of the point reproduces exactly the vegetation of the northern slopes of Mount Pleasant, even down to the occurrence of the rare Gymnogramme rutaefolia in both situations, and the less rare but still xerophytic Clematis afoliata. Hence we must expect to find tussock-grasslands wherever the slopes of the hills are exposed to the full violence of the north-wester. This plant association is therefore to be found from Godley Head to Birdling's Flat. As far as Dyer's Pass there are tussock pastures, with scrub only in the gullies; to the westward there is tussock on the open hillsides and headlands, while somewhat heavier forest at one time existed in the valleys. Owing to the clearing of the “bush,” tussock is now found in many places where once there was forest. Natural tussock-grasslands are again to be found on the northern slopes of Mount Herbert and One Tree Hill, on the far side of Lyttelton Harbour, though in the deeper and more sheltered valleys of Purau and Charteris Bay there was forest. In the latter place it has been removed only during the last ten years. The characteristic herbs of the tussock pasture are Poa caespitosa, Danthonia pilosa, Scleranthus biflorus, Oxalis corniculata,