Despite the profound effects of recent human occupance on the vegetation of New Zealand there still remain many small areas of halophytic vegetation which have been only slightly modified. Most of the coastline directly facing the ocean is comprised of sea cliffs, sand dunes, and shingle beaches, and thus affords little chance for the development of a salt-marsh vegetation. In very sheltered bays and fiords non-halophytic vegetation may reach almost to the water's edge, but there are also many tidal estuaries and bays where extensive areas of salt marshes are present, as in the large and intricate harbours of Auckland and Northland, Nelson Haven and Queen Charlotte Sound, Blueskin Bay and the Otago Harbour area, and the river estuaries of the southern coastline. A generalized ecological account of these salt marshes has been given by Cockayne (1928), while a more detailed study of the halosere has been made by Davies (1931) and Doak (1931). In a few areas the process of shoreline rectification has effected the 'inning' of brackish marshes and lagoons which are non-tidal, though subject to periodic rises in water-level. Of these the most notable are the Ahuriri Lagoon at Napier, of which half of the original area was exposed by the 1931 earthquake and has been subsequently reclaimed; Lake Grassmere in Marlborough, part of which is being converted into a solar salt works; the Okarito Lagoon in Westland; the Te Whanga Lagoon of the Chatham Islands; and Lake Ellesmere in Canterbury, the subject of this study. Small areas of halophytic vegetation also occur inland, especially in the low-rainfall basins of central Otago, mainly in association with exposures of saliniferous Tertiary strata.