Cockayne. — Leaf-variation in Coprosma baueri. 345 



Another New Zealand plant, Olearia cymbifolia, Hook. f., 

 is of interest with regard to the question of flat and recurved 

 leaves. This species is a moderate-sized shrub, and a member 

 of the subalpine scrub of certain mountains in the South Island. 

 Its leaves are small, very hard, thick, tomentose beneath, and 

 much recurved. This leaf-form remains quite constant even 

 when the shrub, is cultivated at sea-level in good garden soil. 

 But occasionally, from the base of such plants, shoots with 

 flat or almost flat leaves are given off, resembling exactly the 

 adult leaves of a closely allied species, Olearia nummularifolia, 

 Hook. f. In this case the recurved leaf is a more stable quan- 

 tity than is that of Coprosma baueri, but the difference is at best 

 one of degree merely, and yet in the case of the Olearia is a 

 plant of which the adult was considered by Sir Joseph Hooker, 

 who was certainly no " species-maker," a distinct species,* 

 whilst its basal reversion-shootsf are clearly, if they should 

 flower, 0. nummularifolia, another of Hooker's species. In 

 such cases as these, and others which could be cited, using only 

 the New Zealand flora, the methods of the systematists appear 

 to break down, and experiment alone can decide as to specific 

 rank. 



Before concluding, I wish to express my thanks to Mr. R. 

 Ewing, of Island Bay, and also to Mr. F. G. Gibbs, M.A., of 

 Nelson, who have sent me a large quantity of fresh material, 

 especially seedlings, in connection with this paper. 



EXPLANATION OF PLATE LIT. 



Photograph of shade leaves on left and rolled leaves of seaside plant on 

 right of Coprosma baueri. Centimeter scale. Photo by the author. 



*Mi. T. Kirk wrote ("Students' Flora," p. 273): " Vai. cymbifolia 

 appears to be a depauperated condition largely caused by the ravages 

 of insects." For a long time I was much puzzled how Kirk could have 

 come to this conclusion, but quite recently Mr. F. G. Gibbs sent me some 

 specimens damaged by insects, such as described above. However, such 

 insect-affected plants are quite rare, and the leaf-form of this species does 

 not in the least owe its shape to such a cause. 



1 1 called attention to this phenomenon some years ago in " A Sketch 

 of the Plant Geography of the Waimakariii River Basin" (Trans. N.Z. 

 Inst., vol. xxxii, 1900, p. 123). At the present time I am making certain 

 definite experiments with this plant, which it is hoped may throw fresh 

 light on its variability. 



