Cockayne — Plants of Chatham Island. 257 



vegetation of the two regions is sufficiently well marked, and 

 that such should occur on two adjacent parts of a very small 

 island is a matter of considerable interest. 



Sandy Seashore. 

 The only portion of this formation examined with any 

 degree of care was the shore in the north of the island, 

 stretching from Wharekauri to Cape Young. Here the shore 

 gradually merges into the dunes by way of very low mounds and 

 ridges. The conditions for vegetation establishing itself and 

 thriving in such a position are very severe, owing to the loose- 

 ness and dryness of the soil, exposure to frequent sea-breezes 

 causing drifting of the sand and excessive transpiration from 

 the leaves of the plants, liability to submersion by salt water 

 at periods of abnormally high tides, more or less salt in the 

 soil at all times, and strong insolation. The sand is rather 

 coarse in texture — much more so, indeed, than in some other 

 parts of the island (Waitangi Beach, e.g.) — and contains an 

 abundance of very small pieces of minute shells. Just above 

 high-water mark grow Calystegia* soldanella and Banun- 

 czdtis acaulis in patches here and there, but forming only a 

 very thin covering on the loose and easily moved sand. The 

 trailing stems of G. soldanella, furnished with a few fleshy 

 leaves, are very short, being rarely more than 4 cm. in 

 length ; the rest of the plant is subterranean, with the ex- 

 ception of the flowers. These latter are large, lilac and 

 white in colour, semiprostrate, with their peduncles buried 

 beneath the sand right to the base of the calyx. This small 

 development of Calystegia contrasts greatly with the same 

 species when growing on sand-dunes at some distance from 

 the sea in many parts of New Zealand. There it forms great 

 masses trailing over the sand, or, when growing in sheltered 

 positions amongst other plants, it actually assumes a climbing 

 habit of growth. Ranunculus acaulis grows in small rosettes, 

 connected together by white underground stems. The leaves, 

 of which there are four or five in each rosette, lie flat on the 

 sand, are ternate in shape, of a rather thick texture, and 

 varnished on the upper surface. The roots are fleshy, seven 

 or eight times as long as the leaves, and descend deeply into 

 the sand. The flower-stem, by the time the fruit is mature, 

 usually arches downwards towards the ground, thus often 

 depositing the ripe achenes below the surface of the sand. 

 This may be merely the result of a mechanical bending of the 



* This Hooker (29, p. 198) considered identical with the European 

 and Australian forms of this species, bui, as he held the opinion then so 

 prevalent that specieR w^re large conjunctive groups, it rnav quite well 

 be that the New Zealand plant differs from the European, or even the 

 Australian, in ccitaiu particulars. 

 17 



