Herriott. — Plants from the Southern Islands. 391 



it is here that Epilobium flourishes well.* It also occurs in the 

 Pleurophyllum meadow of Auckland Island. 



In Campbell Island it is mentioned in the subalpine tussock 

 meadow, where the climate is much more severe than in the 

 lower regions, owing to colder and longer frosts, greater ex- 

 posure to the winds, to the smaller amount of sunshine, and 

 almost constant presence of mist (p. 278). On the rockery this 

 plant is spreading rapidly over rocks and soil, forming large 

 patches of dark-green. 



The change from spiral to dorsi-ventral arrangement of the 

 leaves on the stem is very interesting. The creeping habit is 

 a distinct advantage to the plant in its home on the sand-dunes, 

 for by this means it is able to obtain a firm hold on the some- 

 what unstable surface ; the leaves are then so twisted as to be 

 exposed directly to the vertical rays of the sun when it shines 

 on them, and they are further protected by a thick cuticle on 

 the upper surface. The younger leaves, on the other hand, are 

 more sensitive, and, being arranged spirally, catch the rays 

 obliquely ; and, as a further protection, anthocyanin is present 

 in some of the epidermal cells. On the bleaker subalpine 

 meadow of Campbell Island the creeping habit is also of great 

 advantage in protecting the plant from the winds. 



The leaf-anatomy of the younger and older leaves does not 

 differ in any striking way, except in the presence of a cuticle 

 in the older leaves which is absent in the younger ones, and in 

 the presence of anthocyanin in the epidermal cells of the younger 

 leaves. 



Anatomy (figs. 6a, 66). — The epidermal cells (ep.) consist of 

 one layer of rather cubical cells, protected in the older leaves 

 by a thickened but smooth cuticle. The transverse walls of the 

 cells are thin. Stomata (st.) occur on both surfaces, projecting 

 slightly from the surface. The chlorenchyma (chlor.) is differen- 

 tiated into palisade (pal.) and spongy (sp.). The palisade (pal.) 

 consists of three layers of oval-shaped cells, almost as broad as 

 long, closely packed except beneath the stomata, and densely 

 filled with chlorophyll corpuscles. The spongy (sp.) tissue is 

 very loosely arranged with numerous intercellular spaces (a.s.) ; 

 frequently chains of cells run parallel to the surface (see fig.). 

 There are about six layers of these cells, and all are sparingly 

 filled with chlorophyll. Bundles of raphides (r.) occur in certain 

 of these cells. The chlorenchyma is interrupted by the mass 

 of thick- walled collenchyma (col.) surrounding the main vascular 

 bundle (v.b.), and beneath it is a mass of rounded parenchymatous 



* Cockayne (1903), p. 237. 



