128 Transactions. 



to appear on small oceanic islands, and the order would be the vegetation of 

 rocks, scrub, sand dunes. Examples of islands in this stage are French 

 Rock and Curtis Island. Next, as the land increased in area there would 

 be more gi'ound beyond the reach of salt spray, and stations for land- 

 plants would appear, the order being rocks, perhaps swamp and lake, and 

 finally forest. The destruction of areas of forest by volcanic eruptions or 

 landslips would create new ground where the process of colonising would 

 begin anew, but under entirely different conditions, as the devastated area 

 would be surrounded by forest, which would only be hindered from spread- 

 ing by the barren nature of the soil ; and a new factor so far as the 

 formations here described are concerned is the presence of species of in- 

 troduced plants and animals. On Sunday Island we are able to watch 

 this actually going on, there being two such areas in process of being re- 

 forested. One was caused by a large landslip about four years ago, the 

 other by a volcanic outburst in 1872. 



The last period in the history of the plant formations began with the 

 advent of man. Hardy cosmopolitan plants were introduced, the original 

 formations cleared, and the ground immediately occupied by the new- 

 comers. 



1. Coastal Formations. 



Only such formations as can be called " coastal " in the narrowest sense 

 cf the term are included in this section. Coastal conditions (see 5 ; p. 316) 

 depend upon the distance sea-spray may be carried inland regularly and in 

 large quantities by air-currents, which along the shore almost invariably 

 blow towards the land. For instance, in Denham Bay, which is on the 

 west side of Sunday Island, easterly winds coming over the top of the high 

 cliffs have the efiect of causing an inrush of air along the beach to com- 

 pensate for the withdrawal of air from near the clifi-face. Other factors 

 maldng coastal conditions are salt in the soil, and the Httle Avater-holding 

 capacity of the substratum, which in the Kermadecs is rocks, sand, or 

 pumice. 



(a.) Rocks. — Under this heading I will include the vegetation of rocky 

 shores and shingle beaches. All the coast-lines of the Kermadec Islands, 

 with the exception of Denham Bay and Low Flat beaches on Sunday Island, 

 are rocky, and differ but little in their vegetation. As in the winter months 

 gales are frequent, the vegetation is often drenched with salt water, while 

 during hurricanes the waves break over a considerable tract of land all 

 round the coasts. The smallest quantity of soil on a ledge or in a crevice 

 seems sufficient to support vegetation, which must rely for its existence 

 chiefiy on the abundant rainfall, which, besides supplying moisture, washes 

 down earth from the cliffs above. Plants of Asflenium obtusatum were 

 noticed on the roofs of caves, in which position they depend entirely on 

 the percolation of rain-water carrying sediment through rock-crevices. 



The principal plants composing the coastal rock vegetation are Mes- 

 emhryayithcmum australe, Asplenium ohtusatum, Poa polyphylla, Coprosma 

 petiolata, Samolus repens stricta, Lobelia anceps, Tetragonia expansa, Apinm 

 prostratum, Mariscus ustulatus, Parietaria debilis, and Scirpus nodosus. 



Coprosma petiolata occurs as a low prostrate shrub closely hugging the 

 cliff. On Dayrell Islet, where the vegetation is much exposed, the plants are 

 stunted and about 1 m. high, with exceedingly dense foliage of small rolled 

 leaves. On Fleetwood Bluff the leaf-blades of a male plant measured 

 53 X 21: mm., 54 x 26 mm., 51 x 28 mm., were shining, light green, cori- 



