Foweraker. — Mat-plants and Cushion-plants of Cass River Bed. 29 



(y.) EPHARMONIC VARIATIONS. 



Growing, as this plant does, in all portions of the Cass Valley upon 

 grade 1 terrace, and on moist hillsides, in damp gullies, and on barren 

 mountain-tops, it is but natural that much epharmonic variation should be 

 exhibited. Those mats growing on the bare river-bed or on dry exposed 

 mountain-ridges have a more compact growth-form, shorter branchlets, 

 smaller rosettes, smaller, less membranous, and more hairy leaves than 

 those forms which grow in the moist shady gullies. Plants grown in the 

 greenhouse at sea-level developed an extraordinary length in branchlets 

 and in leaves, which were almost glabrous. 



(8.) Conclusions. 



Considering the various habitats of this plant as a whole, in the 

 majority of cases it is found in moist and more or less shady situations. 

 The forms found in drier and more exposed spots have shorter branchlets, 

 smaller and less membranous leaves. But such exposed plants have the 

 appearance of strangers to their habitat : they have a straggling and 

 unhealthy appearance. Still, the fact that the plant does appear in these 

 drier situations seems to point to considerable powers of adaptation. 



(G.) Raoidia Monroi. 

 (a.) Habitat. 



This plant occurs only on old terrace, and, from the positions in which 

 it grows, appears to require a soil rich in humus and other water-holding 

 material. Occasionally it is found near the edge of the old terrace, and often 

 on the lowest parts of this, bordering on grade 3, but it is totally absent 

 from the various grades of the transition terrace. Its mats seem to be able 

 to grow on any part of the old terrace, and are found in open and exposed 

 situations, as well as in the shelter of tussocks and Discaria. 



(P.) Life-form. 



(1.) General. — An "irregular mat" best describes the growth-form 

 taken by this species. It seldom forms a " pure mat " — i.e., a mat con- 

 sisting entirely of its own vegetative growth— but grows on old consolidated 

 terrace where many plants thrive, some of which are introduced species- — 

 e.g., Trifolium repens, Sagina procumbens, Hypochoeris radicata, Holcus 

 lanatus, Cerastium glomeratum. Indigenous plants occurring among its mat 

 are, amongst others, Hydrocotyle novae-zelandiae var., Anisotome aromatica 

 var., Geranium sessiliflorum var. glabrum, Gnaphalium collinum, Plantago 

 spathulata, and several small species of Carex and Luzula, together with 

 various mosses. When other plants occur to any extent among the mat it is 

 difficult to distinguish the Raoidia itself ; in such cases it does not strike 

 the observer as a distinct individual mat, but its erect branchlets, often widely 

 separated, appear as separate plants struggling with their neighbours. 



The appearance presented by the mat is that of a number of short, erect, 

 greyish-white branchlets, each with two opposite rows of leaves. These 

 branchlets are all that can be seen of the plant, and they grow vertically 

 upwards among the mosses and other low-growing vegetation of the terrace. 

 R. Monroi can hardly be said to exist as a separate mat — certainly not as 

 an entity, as in the case of, say, R. Haastii ; but it, along with various other 

 small plants, forms a thick plant-covering to various parts of the old terrace. 



