[ i°5 ] 
HYBRIDISM IN THE NEW ZEALAND FLORA 
By L. COCKAYNE 
General 
at the present time, when Mendelian methods dominate genetic 
i \ research, and when an assertion that a plant is of hybrid origin 
will not be definitely accepted unless supported by properly-con- 
ducted breeding experiments, field-observations are either ignored, 
or take a quite minor place. Nevertheless, have not such observa¬ 
tions an honourable place in science? Are they not indeed not only 
a necessary preliminary for future genetic studies, but should they 
not teach much that is fairly conclusive regarding the causes of the 
polymorphy so common in a wild plant-population among those groups 
of individuals recognised in floras as “species” and “varieties”? In 
fact, for many years to come, since breeding methods usually demand 
much time, must not field-observations be relied upon to decide, for 
the time being, many critical cases concerning the status of so-called 
“species”? Therefore, in this paper are brought together the results 
of many year’s personal experience in the field, so far as hybridism 
in the New Zealand flora is concerned. 
By those interested in the wider aspects of floristic and ecological 
research the flora and the vegetation of New Zealand are held to 
supply material of peculiar importance. This belief is based partly 
on the extreme isolation of an area with its land-surface, though 
offering climatic and edaphic conditions of many kinds, not too large 
to forbid detailed study; and partly on the diverse composition of 
the somewhat small flora with its palaeozelandic, Australian, palseo- 
tropic, suban tare tic and subcosmopolitan elements 1 . 
The time seems ripe for the publication of information as to the 
natural occurrence of hybrids. Genetic studies have reached a fairly 
high degree of intensity. Lotsy’s suggestive theory of hybridisation 
in regard to evolution 2 cannot be lightly dismissed. The part played 
by indigenous hybrids in floras demands increased investigation in 
the field. It is high time, indeed, that a comprehensive study of the 
1 For details regarding these elements see L. Cockayne, The Vegetation of 
New Zealand (Die Vegetation dev Erde, Bd. 13 ), pp. 314-323, Leipzig and 
New York, 1921. The term “subcosmopolitan” is here substituted for 
‘’ cosmopolitan .’ s 
2 Evolution by means of Hybridization. The Hague, 1916. 
