12 Transaction^ . 



branchlets produce a head. This is cylindrical, about 5 mm. long, and 

 contained by an involucre of three series of bracts The florets are about 

 eight in number, the outer ones pistillate, the inner hermaphrodite. All 

 are tubular. The pappus-hairs are long, almost equalling the corolla. The 

 fruit is an oblong cypsela, slightly hairy. The flowers are very sweetly 

 scented, and the scent given of! from a large mat area is very noticeable. 



(y.) Mode op Growth of Mat. 



The seedling is at first erect and unbranched. The tap-root is long 

 in proportion to the size of the plant, and the leaves are very broad and 

 hairy. As growth proceeds, branches appear in the axils of the leaves, 

 which rapidly elongate, but their growth is obliquely upwards. Subsidiary 

 branches are given off, which are more horizontal than the primary laterals. 

 Soon the proximal portions of the lowest branches come to rest on the 

 ground, owing possibly in part to root-shrinkage. As growth and branching 

 proceed, more and more branches come to lie on the ground, until a disc 

 of radiating stems is formed round the central root. As this centrifugal 

 growth goes on, adventitious roots are given off from the ventral surfaces 

 of the horizontal stems. Vertical branches are also given off, which end 

 in the branchlets. All the horizontal branches have ascending tips. Occa- 

 sionally one side of the mat may grow faster than another, but in most 

 cases there is a growth of practically uniform rate all round the periphery. 

 Mats often spread over large boulders, though the extending branchlets 

 seem to prefer running round a stone to running over it. When branchlets 

 come to a tussock they run up through it and become erect. 



(8.) Epharmonic Variations.* 



The growth-form and morphology given above are those taken from 

 what may be called the " typical " form, but very many variants of the 

 Lw type " occur. As regards the growth-form itself, there is not much 

 departure from the usual type. The chief variations occur in the branchlets 

 and leaves, and may be arranged thus : (i) As in the typical form, but 

 very hairy, so that the general appearance is grey ; (ii) a form with much 

 broader leaves and laxer growth, though not hairy ; (iii) a broad-leaved 

 hairy form. 



(e.) Growth Experiments. 



Plants of different types were taken from their habitat in March and 

 planted in sandy soil in an unheated greenhouse at sea-level. They were 

 abundantly supplied with moisture. The results were : (i) No change in 

 colour during the winter — i.e., no production of anthocyan ; (ii) very rapid 



* In my usage of the term " epharmonic " I have followed L. Cockayne, whose 

 most recent definition (in Cockayne and Foweraker, 1916, p. 169, as footnote) is as 

 follows : " The term ' epharmonic ' is here used as in my former writings — e.g., ' Obser- 

 vations concerning Evolution, derived from Ecological Studies in New Zealand ' (Trans. 

 N.Z. Inst., vol. 44 (1912), pp. 13-30) — with a somewhat different significance to that 

 of Vesque and Warming (see ' Oecology of Plants ' (1909), pp. 2 and 369). According 

 to my usage, an epharmonic variation is a change in its form or physiological behaviour 

 beneficial to an organism evoked by the operation of some environmental stimulus. 

 Such a change may be called an epharmonic adaptation, as distinguished from such adapta- 

 tions as cannot be traced to any direct action of the environment. To the neo-Darwinian 

 no permanent adaptation according to the above definition would be ' epharmonic,' 

 whereas to the neo-Lamarckian all would be so considered." 



