344 Transactions. 



concerned, between shade leaves and normal sun - and - wind 

 leaves. 



Whether in the case of Coprosma baueri a leaf having once 

 become possessed of a recurved margin can again become flat, 

 or an extreme rolled leaf unroll itself, is a matter requiring 

 investigation. It seems to me, however, that there is a strong 

 tendency in the plant to produce recurved leaves, and that such 

 under normal conditions are characteristic of the species. Seed- 

 lings have flat leaves, but there is sometimes a trace of recurving, 

 especially at the base of the lamina. As for the leaves of semi- 

 sucker shoots referred to above, their being flat might in part 

 be attributed to their being reversion-shoots, since such are 

 especially wont to make their appearance at the bases of plants. 

 The large size of such leaves may also in part be due to the 

 well-known luxuriant growth of suckers. All the same, many 

 of the shoots observed were clearly not suckers, and there is no 

 doubt but that shade and absence of wind played a most im- 

 portant part with regard to the leaf -form. 



Of course, the rolling of a leaf and consequent reduction 

 of leaf-surface in a xerophytic station is very beneficial for the 

 well-being of the plant, but that such is a benefit is no explana- 

 tion of why such rolling should occur ; it only explains in part 

 how the plant in question can exist in its particular station. 

 On the other hand, the presence of rolled leaves where exposed 

 to sun and wind, and of flat leaves in the shade and in a still 

 atmosphere, points to the wind factor and the light factor, one 

 or both, as having been instrumental in originally causing these 

 structures, which now they are able to evoke, thanks to an 

 hereditary tendency in the plant to respond to their stimulus. 

 Were there no plants of Coprosma baueri except those of ex- 

 posed stations on the coast, then large, flat leaves would be 

 unknown, and the rolled-leaf form would be held to come " true " 

 from seed. Or, again, were there no stations suitable for the 

 tree form, only the prostrate form would exist. That this is 

 not an absurd suggestion is shown by the fact that another 

 New Zealand coastal tree, Myoporum latum, Forst. f., only ex- 

 ists on the Moko Hinou Islands as a prostrate shrub, and were 

 that its sole habitat its power of becoming a tree could never 

 be dreamed of. Such plastic species, indeed, have really no one 

 fixed form, but as Klebs* has shown (if I understand him rightly), 

 their so-called normal characters are merely a few of a larger 

 series, and are of no greater specific value than those others 

 which may be evoked by a different environment. 



* " Wil Ik in-lithe Entwickelungs anderungen bei Pflanzen," Jena, 1903, 

 pp. 145-46; indeed, the whole of chapter vii, |>. 139 et seq, requires con- 

 sulting. 



