The Sources and Distribution of the New Zealand 
Flora, with a Reply to Criticism. 
BY 
J. C. WILLIS, M.A., Sc.D. 
With seven Figures and Map in the Text. 
Contents. 
PAGE 
General . . . . *.. . . 339 
Other Factors than Age active.348 
Are Endemics chiefly Relicts?.349 
The Relative Age of Trees, Shrubs, and Herbs, and the Sources of the 
New Zealand Flora. 354 
Age tends to extinguish Old Species?.362 
A NUMBER of reviews and criticisms have lately appeared, supporting 
or attacking my hypothesis of ‘age and area’. Two ( 11 , 12) by 
Professor Sinnott are of particular interest, and follow lines which he has 
more fully developed in earlier publications ( 13 , 14 ). In replying to these 
criticisms I shall endeavour, as much as possible, to use new facts, or new 
presentments of facts, about the flora of New Zealand and its surrounding 
islands, a flora which is of great interest when examined in the light of age 
and area. 
The employment of this hypothesis suggests new methods of attacking 
the facts of geographical distribution, and has led to the discovery of clear 
evidence in favour of certain hypotheses which in the past have been the 
subject of much discussion. It is, for example, as will be seen below, 
rendered probable that the peopling of New Zealand with plants was by 
way of land bridges, and that there were at least two of these, one northern, 
leading to some part of Indo-Malaya, and one southern. By the former 
the arrivals were mainly trees and shrubs, by the latter herbs. I regret 
that my reply must to some extent take the form of a criticism of the 
very interesting hypotheses that Professor Sinnott has brought forward in 
his various papers, but they are too important in their general bearings 
upon botanical and evolutionary science to pass without comment, especially 
as they do not rest upon definite proof, but upon a masterly presentment 
of probabilities. 
Professor Sinnott’s chief points, as I understand his papers, are : 
(1) That my hypothesis is an assumption. 
LAnnals of Botany, Vol. XXXII. No. CXXVII. July, 1918.] 
