248 Transactions. — Botany. 



proportion to the height of the trees. Moreover, the dense 

 loot of the forest assists in keeping its interior cahn, and here 

 the hygrophytic factors can exercise full sway, so that the 

 vegetation within the forest is of the most extreme hygrophytic 

 character, and its constituents the filmy ferns, liverworts, &c., 

 such as can endure only for a very limited period dry air or 

 exposure to direct sunlight. The light factor, indeed, is a very 

 important one so far as many of these forest plants are con- 

 cerned. Feeble light is of as much importance in the cultiva- 

 tion of certain liverworts and filmy ferns as is moist air, and 

 the letting-in of more light into a New Zealand rain-forest 

 when timber is being removed has perhaps the most to do 

 with the death of a large percentage of the hygrophytes. 



This rata forest of the Auckland Islands is by no means 

 altogether an endemic plant-formation. Very similar forests 

 are found in certain parts of the South Island of New Zealand 

 and in Stewart Island, but they contain more arborescent 

 components — notably, Weinmannia racemosa is a frequent 

 member ; nor is the general physiognomy the same. This 

 interesting fact — the occurrence of a very similar formation 

 in two regions so distant — is discussed when dealing with the 

 history of the vegetation. 



Since all the plants of this formation, if we except the 

 fern Polypodium rigidum, occur in New Zealand proper but 

 little need be said here as to the life -forms of most of 

 them. The general aspect of Metrosideros lucida has been 

 sufficiently described above ; its lanceolate, thick, coriaceous, 

 shining green leaves furnished with numerous oil-glands, their 

 blades + 3-6 cm. x ±1-6 cm., growing closely together, are 

 quite able to withstand the most violent winds so long as the 

 atmosphere is charged with moisture. On the dry Canterbury 

 Plain the hot north-west winds do not allow this tree to be 

 brought into cultivation, whereas in Dunedin, where this wind 

 is unknown or extremely modified, the rata flourishes in 

 gardens, though noD a member of tiie forest of that locality. 

 The narrow semi- vertical needle -like leaf-blades of Draco- 

 ■phyllum loncjifoliuvi have their transpiring surfcice still more 

 reduced by the concavity of the upper (inner) surface, and are, 

 moreover, confined to the extremities of the ultimate branch- 

 lets. Like Dracojjhyllum arhorcum of Chatham Island (22, 

 p. 294), Drac. longi/oliiim has juvenile leaves broader than 

 those of the adult, and it also frequently puts forth "rever- 

 sion-shoots," as mentioned above. Such shoots have leaves 

 much broader and longer than those of the adult, and they 

 closely resemble the juvenile leaves. In the juvenile leaves 

 the position with regard to light is different from that of the 

 adult leaf, the surface of the former being almost horizontal, 

 while the latter is semi-vertical. There are also differences 



