CHAP. XXII THE FLORA OF NEW ZEALAND 505 



with these indigenous and well-estabUshed plants, and only 

 in a few cases were able to obtain a footing; whence it 

 arises that we have many Australian types, but few 

 Australian species, in New Zealand, and both phenomena 

 are directly traceable to the combination of great powers of 

 dispersal with a high degree of adaptability. Exactly the 

 same thing occurs with the still more highly specialised 

 Orchidese. These are not proportionally so numerous in 

 New Zealand (thirty-eight species), and this is no doubt 

 due to the fact that so many of them require insect- 

 fertilisation often by a particular family or genus (whereas 

 almost any insect will fertilise Compositae), and insects of 

 all orders are remarkably scarce in New Zealand.^ This 

 would at once prevent the establishment of many of the 

 orchids which may have reached the islands, while those 

 which did find suitable fertilisers and other favourable con- 

 ditions would soon become modified into new species. It 

 is thus quite intelligible why only three species of orchids 

 are identical in Australia and New Zealand, although their 

 minute and abundant seeds must be dispersed by the 

 wind almost as readily as the spores of ferns. 



Another specialised group — the Scrophularineae — 

 abounds in New Zealand, where there are sixty -two species ; 

 but though almost all the genera are Australian only three 

 species are so. Here, too, the seeds are usually very small, 

 and the powers of dis^Dersal great, as shown by several 

 European genera — Veronica, Euphrasia, and Limosella, 

 being found in the southern hemisphere. 



Looking at the whole series of these Australo-New 

 Zealand plants, we find the most highly specialised 

 groups — Composite, Scrophularinese, Orchidese — with a 

 small proportion of identical species (one-thirteenth to one 

 twentieth), the less highly specialised — Ranunculacese, 

 Onagrarise and Ericeae — with a higher proportion (one- 

 ninth to one-sixth), and the least specialised — Juncese, 



1 Insects are tolerably abundant in the open mountain regions, but very 

 scarce in the forests. Mr. Meyrick says that these are " strangely deficient 

 in insects, the same species occurring throughout the islands ; " and Mr. 

 Pascoe remarked that "the forests of New Zealand were the most barren 

 country, entomologically, he had ever visited." {Proc. Ent. Soc, 1883. p. 

 xxix. ) 



