INTRODUCTORY ESSAY. 



much. Enough has been adduced to show that this subject is most difficult and obscure, and I may 

 add that it is one in which hasty generalization from first impressions has given rise to much < 



2. Genera whose species alter in form or habit. These are — Hymenanthera, Pittosporum, Plagi- 

 anthus, Melicope, Discaria, Edwardsia, Carmichmlia, Ackama, Panax, Aralia, Carpodetiu . Coprosma, 

 Parsonsia, Oka, Weinmannia, Dammar a, Thuja, Podocarpus, Dacrydium, Phyllocladus, Rhipogonum. 



Many of the above vary so remarkably that botanists have been greatly puzzled by the abnormal 

 forms they present : thus a state of Hymenanthera crassifolia has been referred to Goodenia, one 

 species of Weinmannia has been made into two genera, and an Olea has been converted into a 

 Metrosideros. Some states of Plagianthus urticinus and of Carpodetus serrdtus (plants of two very 

 different Natural Orders) are almost tmdistinguishable, and so are Hymenanthera crassifolia and 

 Pittosporum obcordatum ; so also Melicytus micranthus, Panax anomala, and Melicope 

 are often so extremely like one another in foliage as to be confounded when in a dry state. "With 

 regard to Carmichmlia, Ackama, Weinmannia, most of the Araliacece, Coprosma, Parsonsia, and 

 some of the Pines, the variation is greatest in amount between old and young plants; but with 

 Discaria, Hymenanthera, Pittosporum, some species of Coprosma, Olea, aud many Pines, there seems 

 to be no law, abnormally formed organs appearing on the same branches with normal ones. 



From the above list it would appear that variability of this nature is most frequent amongst 

 more or less endemic genera and species, but whether in this respect the New Zealand Flora is more 

 variable than others I have not proved. The Yew, Cedar, Holly, Ivy, and especially Furze and 

 Juniper, perhaps vary in Europe as much as, or more than, the above ; but it is difficult to appre- 

 ciate the amount of variability in a familiar object. On the whole I am inclined to think that the 

 New Zealand Flora is remarkable for the number of plants which vary thus, but that this peculiarity 

 is rendered conspicuous by the prevalence of Coniferce and Araliacete, which are variable in all pans 

 of the world. 



