68 Transactions. 



of the group comprising Olearia ilicifolia together with 0. macrodonta, 

 where the extremes of the linear series of intergrading forms receive, 

 specific rank. 



The case of Veronica salicifolia Forst. f. may be next examined. The 

 species, as defined by G. Forster in the Prodromus, probably originally 

 referred to one or two plants at most,* but in the Manual the meaning has 

 been greatly extended, so that the species, according to Cheeseman, con- 

 tains three named varieties, a typical form which is not strictly defined, an 

 unnamed variety from the Kermadecs,")" and, in addition (Manual, p. 504), 

 " numerous forms which appear to connect it with V. macroura, Dieffen- 

 bachii, macrocarpa, ligustrifolia, and others." What is meant in that sen- 

 tence by the word lt it " is vague, but it seems as if the type was thus 

 indicated, while the varieties and intermediates are something different. At 

 any rate, at one end of the series would be the " type " (whatever that may 

 be), and at the other end one or other of the above species ; or the whole of 

 them, together with the "type,"' its varieties and the "intermediates," 

 might constitute one huge aggregate. 



Still another class of aggregate species is that large one said to be 

 " variable," but where few or no varieties are defined. Agropyron scabrum 

 Beauv., Danthonia semiannularis R. Br., Veronica pinguifolia Hook, f., and 

 Celmisia discolor Hook, f., along with many other species, belong to this 

 category. Usually no plant answering to the description of such species 

 exists in nature. 



Finally, species may be highly polymorphic, but no mention be made of 

 such tv variability." Thus Acaena Sanguisorbae Vahl is not spoken of in 

 the Manual or by Hooker in the Handbook oj the New Zealand Flora as 

 variable, and yet Bitter, in his recent memoir on the genus, J has clearly 

 shown that the species is a most puzzling complex, while my preliminary 

 experimental studies are suggesting that his numerous subdivisions are 

 insufficient. 



The other great class of species is that which the layman practically 

 concerned with plants — e.g., the gardener — alone recognizes as such ; that 

 is, those in which there is no manifest variation§ except such as is quite 

 unstable and caused by the environment of the varying individual. The 

 Manual contains many species of this character, || of which Agathis au straits 

 Salisb., Dacrydium cupressinum Sol., Carmichaelia gracilis J. B. Armstg., 

 and Celmisia bellidioides Hook. f. may be taken as examples. 



The conception of a species as put forth by its author has been fre- 

 quently modified not merely by other taxonomists, but by the author 

 himself, and this without any statement to that effect. Generally a fairly 

 invariable species is thus transformed into an aggregate, but occasionally 

 the opposite course has been followed. The citation of the original author's 



* Regarding Forster' s type see certain remarks bv myself in Trans. N.Z. Inst., 

 vol. 48, p. 201, 191(5. 



t Now Veronica breviracemosa W. R. B. Oliver. 



% G. Bitter, Die Gattung Acaena, Bibliotheca Botanica, Heft 74. pp. 1-336. 1910, 

 1911. 



§ In the case of certain species there is frequently a quite constant form in cultiva- 

 tion which owes its constancy either to being a microspecies or to all its members being 

 the vegetative offspring of one individual. Veronica Barkeri Cockayne is a case of this 

 kind, as is also the ordinary form of V. Dieffcnbachii Benth. 



|| Of course, without actual breeding experiments it is impossible to know whether 

 any species is really a true-breeding entity, so the word " many " can be taken for what 

 it is worth. 



