L. Cockayne and Fowehake^. —Plant Associations at Cass. 169 



proach nearer and nearer to growth-forms of species limited to the one 

 environment or the other, then it is safe to conclude that the induced 

 apparently epharmomc* forms are truly xerophytic or mesophytic as the 

 case may be. Certam species from the Cass shrubland exhibit such induced 

 xerophily or mesophily to an astonishing degree, as L. Cockayne showed 

 some time ago.f 



A most interesting case of a contrary character came under our notice 

 while studying the Cass shrubland for the purposes of this paper On coarse 

 stony debris, as will be seen farther on, Podocarpiis nivalis, the mountain- 

 totara, is extremely abundant, its shoots far-spreading and closely hugging 

 the ground m espalier fashion. This, so far as we had previously noted 

 was the invariable behaviour of this shrub in such a station But' 

 according as the plant grows in sun or shade in various parts of New 

 Zealand, so does it assume the prostrate or the more or less erect habit t 

 However, on this debris slope at Cass there are certainly two distinct 

 hereditary races of the species, one the typical P. nivalis Hook f which 

 m tJie above habitat always remains prostrate, and the other, which grows 

 m apparently exactly the same habitat, is a dense shrub 1-8 m. high or more 

 <see mte A V, fag. 2). Here, then, a special xerophytic growth-form the 

 spreading prostrate (espalier), is not, apparently, one whit better silted 

 tor Its habitat than the more mesophytic, infinitely less wind-resisting, erect 

 shrub-form, which, moreover, from its position should be exposed to a 

 more intense transpiration. The word "apparently" is used advisedly 

 since the erect shrub may have a longer root-system, and so be under a 

 dilterent environment to the prostrate form. 



The Cass shrubland associations are not peculiar to the area, but, with 

 slight floristic modifications, extend throughout the Eastern and North- 

 eastern South Island Botanical Districts, though the latter possesses some 

 shrubland peculiarly its own.§ Excepting the open shrubland, and perhaps 

 the Leptospermum thicket, the associations are virtually primitive 



The shrubland associations here dealt with may be designated as follows • 

 (a) Cassmia open shrubland ; (b) Discaria (wild-ii'ishman) thicket • (c) Levto- 

 ^permum (manuka) thicket ; (d) river-terrace and debris scrub. 



(a.) Cassinia Open ShruUand. 



dominate IS at the present time a common feature in much of lowland 

 and montane New Zealand, especially on coastal areas from which Te 

 forest has been removed by man. In primitive New Zealand, associations 



* The term " epharmonic " is here used as in mv former writincr^ ^ ., " ni 

 ™.o.j, „„„„„„;„, Evolution c,„i,e4f,-om^^^^^ 



a„d It '• ''■^- '"'^'- ™'- '' <'=*"'■ P- '-=•■ ""'' -'^.-oLa (1912), pp. 15, ,7, 20, 

 t Trans. N.Z. Inst., vol. 44 (1912). p. 17, and lor figure see pi. 4 facinr o 21 



