174 Transactions. 



(4.) Swamp. 

 Every transition from lake to tussock grassland is to be seen at Cass; 

 but our data is quite insufficient for even a superficial treatment of the 

 subject, consequently our remarks are confined to swamp. But, even in 

 tbis regard, the details, on wbicb so mucb depends, of tbe relation between 

 the species and the depth of the water cannot be given. By " swamp " 

 we mean an association growing in a habitat where water remains per- 

 manently, or at least during the greater part of the year, on the surface of- 

 loose, frequently peaty, soil, while it is not too deep to inhibit the presence 

 of plants rooting in the ground. This formation varies considerably in 

 character in different parts of New Zealand, while, except forest, no form- 

 ation has been so greatly altered by man. The Cass swamps, then, since 

 they are virtually in their primitive condition, stand as most important 

 natural objects, to be jealously guarded and assiduously studied. The 

 piece of swamp close to the biological station supplies a fine example of 

 the gradual change from glacial lake to dry ground by way of swamp. 



The swamp belongs to the class " reed-swamp," and to that association 

 where Typha angustifolia var. Muelleri is dominant — raupo (Typha) associa- 

 tion. 



The vegetation exhibits a fairly well-marked series of girdles which 

 are in harmony with the depth of the water, but the effect is ^o some extent 

 masked by streams of running water passing through the swamp, and 

 by non-uniformity of depth in places between the centre and margin. 

 Speaking generally, there is a piece of open water in the centre of the swamp 

 too deep as yet for occupation by swamp-plants ; next comes a girdle of 

 raupo {Typha angustifolia var. Muelleri) ; next a girdle of Carices and 

 other plants ; then the shore girdle, which is subject to periodical sub- 

 mersion; and, finally, boggy ground, usually beyond the reach of flooding. 

 Our notes do not permit exact details of the composition, or even the 

 limits, of these girdles. 



The Carex girdle has as its dominant species the niggerhead, Carex 

 secta, which species in places invades the Typha area. Growing with the 

 above Carex is more or less Phormium tenax. Where the water is sbal- 

 lower the grass-like Carex Gaudichaudiana is easily dominant, forming a 

 broad girdle.- With it are other plants — e.g., Epilohium pallidifiorum — • 

 but we have no precise details. 



At the margin of the swamp proper there is a considerable assemblage 

 of species, which, though here taken together, do not all grow under the 

 same conditions. The following may be mentioned : Carex Gaudichaudiana 

 (stunted), C. ternaria, Schoenus panciflorus, Juncus polyanthemos var., 

 Luzula campestris var., Rumex flexnosus, Montia fontana, Potentilla anserina 

 var. anserinoides, Geranium microphyllum, Viola Cunninghamii, Halorrhagis 

 micrantha, Hydrocotyle novas-zelandiae var. montana, Oreomyrrhis andicola 

 var., Mazus radicans, Plantago triandra, Aspenda perpusilla, Celmisia 

 longifolia var., Gnaphalium paludosum. 



Schoenus panciflorus plays an important part in the marginal physiog- 

 nomy of the swamp, since in no few places it forms almost pure patches. 

 This sedge of the tussock-form is especially characteristic of shallow gullies, 

 where it grows in company with Sphagnum and forms a distinct bog 

 association. Common species of such a habitat are : Blechnum penna 

 marina, Poa eaespitosa var., Hierochloe redolens, Carex ternaria, C. Gaudi- 

 chaudiana var., Viola Cunninghamdi, Hydrocotyle novae - zelandiae var. 

 tnontana, Aciphylla sqiiarrosa var., Asperula perpusilla, Wahlenbergia albo- 

 inarginata, Celmisia longifolia var., Olearia virgata var. 



