190 SUBANTARCTIC ISLANDS OF NEW ZEALAND. [EcoIdijIciiI Botanil. 



compound umbels joined together into a globose head which is about 12 cm. deep 

 and 19 cm. across, and terminates a pale-green fistular stem about .32 cm. in 

 length. 



Suttonia divaricata is a typical example of the divaricatingly branched shrubs 

 dealt with at some length further on. It is sometimes almost a small tree, in which 

 case there is a naked main stem or stems and a flattened head of interlacing but 

 somewhat weeping twigs. The leaves are small, obovate or obcordate, about r.3 cm. 

 long, dark- or yellowish-green, coriaceous, dotted with glands. The flowers are 

 minute. The fruit is small, globose, fleshy, and purple. 



The species of DrncophijUum are speciallv dealt with further on. 



3. The Ecological Factors. 



It is onh' possible at present to speak in most general terms of those agents 

 on which the presence of the various life-forms and their distribution depends. It 

 is premature to attempt the reduction into its constituents of that general condition 

 known as "climate"; nor is this so necessary as in those regions where there are 

 great extremes of heat, light, and so on. 



The subantarctic climate, owing to latitude and the position of the islands in 

 a great body of water, is a most equable one. Between the mean temperature of 

 summer and winter, or even between their extremes, there is little difference. A sky 

 constantly cloudy, rarn for a longer or shorter period almost daily, an atmosphere 

 ever saturated with moisture, brief periods of sunshine, a general average low tem- 

 perature with but slight frosts at sea-level during winter, constant cold and violent 

 winds, accompanied with showers of rain, or sleet, or snow, even in summer — such is 

 the general climate of the islands under consideration. There are no records as to 

 the climate of the hills, which in the Aucklands rise to a height of 600 m., but un- 

 doubtedly they experience in winter a good deal of frost. The ground near the summit 

 of Mount Honey, in Campbell Island, was frozen hard at the time of my visit in 

 June, 1903, whereas at sea-level on the same day there was little or no frost. But 

 even on the hills I doubt much if the cold is ever very severe, or of long duration, 

 or that it falls below —9° C. at most. 



If we must separate from the remainder one factor, it will be the wind, whose 

 mark is on the vegetation everywhere, both with regard to form and distribution. 

 Especially is constant wind antagonistic to tree-growth, and these islands strikingly 

 bear out this statement. Low forest, composed, however, of but few species of 

 trees and shrubs, forms in many parts of the Auckland Group a belt along the shore, 

 most luxuriant where there is most shelter, but wanting in especially exposed situa- 

 tions. Moreover, this forest, as is seen further on, has adapted itself to the wind- 

 conditions. On Campbell Island, where the smaller land-surface and general con- 

 figuration affords less shelter, there is no forest, its place being taken by a dense 

 growth of shrubs analogous to a similar formation on the Aucklands above the 

 forest-line. On Antipodes, a smaller island still, the scrub is stunted to an extreme 

 degree, and is found only in sheltered gullies, or hidden by the tall tussock-grass. 

 Finally, on Macquarie Island, at a latitude corresjiondino; with that of north York- 

 shire, woody plants are altogether wanting. 



