Oliver. — Vegetation and Flora of Lord Howe Island. Ill 



Drv ground : On exposed ridges on the Northern Hills, where not 

 occupied by scrub, rocky ground supports a miscellaneous lot of herbaceous 

 plants. Those noted in this situation were Poa caespitosa, Dickelackne crinita, 

 Polycarpon tetraphyllum, Oxalis corniculata, Cynodon dactylon, Gnaphalium 

 luteo-album, Sonchus oleraceus, Scirpus nodosus, Sporobolus indicus, and 

 Bidens pilosa. 



9. Mangrove. 



On a shingle beach between tide-marks at the north end of the lagoon 

 there are a few detached plants of Avicennia officinalis. Farther south, 

 near the mouth of Deep Creek, Aegiceras corniculatv/m occurs. 



Geographic Relationships of the Forest Formations. 



The forest which clothes the greater part of Lord Howe Island is a 

 temperate rain forest. Except for the absence of gymnosperms it agrees 

 closely in essential characteristics with the rain forests of New Zealand 

 and Tasmania, and apparently with the forest along the northern rivers 

 of New South Wales and the " vine scrub " of south Queensland. It is 

 quite unlike the Eucalyptus forest of Australia and Tasmania. 



The moss forest of Mount Gower is similar to that on Sunday Island 

 and on high ground in the North Island of New Zealand, especially where 

 clouds are frequent. The most accessible example occurs on Te Aroha 

 Mountain, while an apparently similar association is described by Cockayne 

 {Report on Waipoua Kauri Forest, p. 14, 1908) as occurring on the upper 

 slopes of Toetoehatiko. south of Hokianga. 



III. ORIGIN OF THE FLORA. 

 Geological History of Lord Howe Island. 



Between New Zealand and the islands of the tropical Pacific is an 

 expanse of ocean broken on the surface only by the three island groups 

 of Lord Howe, Norfolk, and the Kermadecs, but with a most irregular bed. 

 Study of a map showing ocean-floor contour-Lines reveals the presence of 

 two submarine ridges extending from New Zealand in northerly directions. 

 The Kermadec ridge extends as far northward as the Samoan Group. To 

 the eastward of it is an unbroken expanse of ocean over 5,000 m. in depth. 

 A broader submarine ridge trends from New Zealand towards New Cale- 

 donia and tropical Australia. Its western edge is comparatively high, 

 a continuous raised ridge less than 1,800 m. stretching from the South 

 Island of New Zealand to the latitude of New Caledonia. It is on the 

 extreme western limit of this that Lord Howe Island is situated. 



The eastern edge of the broad ridge presents a more uneven surface, 

 being between the northern peninsula of New Zealand and New Caledonia 

 raised in a line of detached portions coming within 1,800 m. of the surface. 

 One of these raised portions reaches the surface at Norfolk Island. Between 

 the Lord Howe Island ridge and Australia is a deep trough, over 4,000 m. 

 in depth, stretching as far north as S. lat. 25°. 



Assuming the comparative permanence of the main features of the 

 ocean-floor, at least during Tertiary times, these ridges would indicate 

 that at a former period of upheaval Lord Howe Island would be in closer 

 touch with New Zealand and New Caledonia than it would with temperate 

 Australia. The presence of this remarkable submarine ridge is the only 



