NEW ZEALAND—EGBERT H. WALKER 339 
be of interest. In the first place, there are few annual or biennial 
plants in the native flora. Then it is striking that many genera, 
which in other parts of the world have mostly herbaceous species, 
here have only or mostly shrubby ones. Why the long-isolated New 
Zealand flora should have developed a flora without annuals and 
biennials and with this emphasis on woody plants is somewhat puz- 
zling. ‘There were no grazing animals in New Zealand until the white 
man came, except possibly the large extinct flightless bird, the moa. 
Hence, the course of evolution may have been slightly different from 
what it was in other countries where grazing animals could have 
influenced the development of the flora. 
A puzzling characteristic of about 200 species in 32 different families 
is the development of different types of foliage and growth habits at 
successive stages in an individual plant’s life. In its youth, which 
may extend from a month to 50 years, a plant may have a “juvenile 
foliage,” and then develop a strikingly different “adult foliage.” 
These may be so different that one finds it difficult not to doubt the 
veracity of the local botanists who point out that these different forms 
of foliage really occur on the same plant and that they do not repre- 
sent different species. Furthermore, many of these plants in one 
stage are adapted to one habitat and in the other are better fitted to 
live in a different environment. Most of these species are endemics, 
so the phenomenon seems in some way related to the evolution of the 
New Zealand flora. Are these changes related to past changes in the 
climate of New Zealand, and are the plants now reflecting their evolu- 
tion in the stages of development through which the individual plant 
passes? The phenomenon is a very puzzling one. It is by no means 
confined to New Zealand, but is more strikingly evident here than in 
other parts of the world. At any rate this feature has advantages 
to the plant propagator, for sometimes in cultivation it happens that 
the “juvenile” stage is more susceptible to an insect or fungus attack 
than is the “adult” stage. In that case the grower can vegetatively 
propagate from ‘‘adult” plants, thus entirely eliminating the sus- 
ceptible stage in the development of his plants, unless the adults so 
grown take a notion to revert to the juvenile habit of growth. Often 
change to another stage can be induced by altering the growing con- 
ditions of plants under cultivation. 
Another disconcerting phenomenon to the student of species of the 
taxonomist is the extreme variation of form that may be found within 
a genus. A genus may have species which are diminutive in size and 
others that are huge trees. The taxad Dacrydium is an example. 
This phenomenon occurs in other countries also but it seems to be 
outstanding here. Great variation within certain species is also very 
disconcerting, as is the running together of the species in many genera 
such as Coprosma (Rubiaceae). Hybrid swarms are common and 
