388 * Transactions. 



Hab. — " Campbell's Island ; in rounded tufts on rocks near 

 the summit of the hills, at altitude 1,000 ft. ; of rare occurrence, 

 and confined to the tops of the hills on Campbell Island ; no- 

 where seen in Lord Auckland Group. . In the Falklands, and in 

 Fuegia where it was discovered by Banks and Solander, it is 

 very common, both on the low grounds and on the mountains."* 



This is one of the small rock-plants which find a habitation 

 in the crevices of the rocks where a small amount of peat has 

 been able to collect, while the moisture of the atmosphere makes 

 life possible (fig. 46). 



The other species, Colobanthus muscoides, from which this one 

 differs by being rigid and more pungent,* is more widely dis- 

 tributed throughout the islands. Below the green leaves of this 

 species — that is, in the centre of the cushion — " the old leaves 

 are all in a greater or less advanced stage of decay, and form 

 a dense, yellow, sticky, peaty mass, about 10 cm. in depth, 

 through which the shoot-axes penetrate, giving off at the under 

 surface of the cushion a large number of fine roots. The peaty 

 mass absorbs water like a sponge, and in the wet climate must 

 nearly always be saturated with moisture. "f 



In its natural habitat it is probable that Colobanthus subulatus 

 behaves in the same manner, but on the rockery, where the 

 conditions under which it has to live are not so stringent, the 

 older leaves have not degenerated into the " sticky, peaty mass." 

 That it still maintains many of its xerophytic characters may 

 be seen on a study of its anatomical structure. 



Anatomy (figs. 4a, 46). — There is firstly a thickened but 

 unwrinkled cuticle, then come the epidermal cells, on the upper 

 surface (ep.) very thick- walled but flattened, and on the con- 

 vex side (l.ep.) still with thickened walls, but larger and more 

 cubical in shape. There are numerous small stomata (st.) on 

 the upper surface, with a few on the convex side just near the 

 upper epidermis. The chlorenchyma (chlor.) may perhaps be 

 said to be differentiated into palisade {pal.) and spongy (sp.). 

 The palisade is found in three layers of small elongated cells 

 on the upper surface, and for a greater or less distance is con- 

 tinued down the sides of the convex portion of the leaf. The 

 rest of the leaf is composed of larger cells, more or less round 

 in shape, containing very little chlorophyll. The chlorophyll 

 is mostly confined to the palisade cells. There are two or three 

 vascular bundles (v.b.) enclosed in a large thin-walled paren- 

 chyma sheath (p.s.) and imbedded in a mass of colourless thin- 

 walled parenchyma (par.). 



* Hooker (1847), p. 13. 

 t Cockayne (1903), p. '242. 



