Cockayne. — Boianical Excursion to Southern Islands. 317 



Olearia is closely allied to "the antarctic or subantarctic 

 genus Ghilotrichmvi, a genus of three species, one of the 

 numerous connecting-links between the Australian and ex- 

 tra-tropical or Andine South American floras. This genus 

 is closely allied as well to Olearia of the former as to 

 Diplostephium of the latter region." Olearia lyallii belongs 

 to a distinct division of the genus confined to the New 

 Zealand area, distinguished by their large solitary heads, 

 usually solitary on terminal peduncles, but in one species with 

 simple 3-8-flowered racemes. Kn-k has called this section of 

 the genus the macrocephalous Olearias. Besides the flower- 

 heads, the foliage is very distinct. With one exception, the 

 xerophytic 0. msignis, they all occur in the very wettest 

 regions of the South Island or on the Chatham Islands, 

 Stewart Island, and the Southern Islands. 0. lyallii is very 

 closely allied to 0. colensoi of Stewart Island and the western 

 subalpine scrub in the South Island. 



The extraordinary plasticity of many New Zealand plants, 

 shown by the great changes in leaf-form which can be quickly 

 brought about by culture under conditions different to what 

 tiaey experience in nature, and the striking heterophylly ex- 

 hibited in a state of nature by a great number of plants, points 

 distinctly to the species being by no means in harmony with 

 their present surroundings. Discana toumatou cultivated in 

 moist air no longer produces spines, but in their place are 

 drooping leafy shoots. Many species belonging to the genera 

 Baoulia, Veronica, and Carviichaelia, all most characteristic 

 New Zealand genera, will revert to the seedling form by culti- 

 vation in moist air or feeble light (see PI. XXII.) , or under the 

 same conditions the seedlings in some cases will never assume 

 the adult form. The case of New Zealand xerophytic shrubs 

 as affording evidence of the Pliocene land -extension has 

 already been cited. 



As for further evidence regarding land - connection with 

 South America, no more need be said except to point out the 

 great resemblance between the flora of Kerguelen Land and 

 that of Macquarie Island. In this latter island no fewer than 

 nine out of twenty-seven species are Fuegian, and if we omit 

 the endemic species of Kerguelen Land, including Poa cookii 

 as such, six out of the remaining fifteen species occur on 

 Macquarie Island, amongst which is the wonderful Azorella 

 selago, which does not extend to any of the other islands. 



Whether all the Southern Islands have formed a part of 

 New Zealand during its one, or it may be more, southern 

 extensions is a debatable point. Filhol (35a), from geological 

 evidence collected on the island during a stay of a consider- 

 able period, claims that Campbell Island has always re- 

 mained isolated. Hector, on the contrary, considers that 



