354 Tra77sactions. 



the process is a slow one, which, however, may be much accelerated by a 

 stream depositing shingle, &c., on the lake-floor. 



* Lakfl. 



The most important lake is Lake Heron, situated at about 670 m. above 

 sea-level. There are several smaller lakes on the Upper Ashburton Plain, 

 also tarns on spurs which were formerly overridden by the ice, as well as 

 small ponds in various places. 



We have no details as to the lake-vegetation beyond the facts that 

 Typha angustifoh'a var. forms the innermost girdle in some parts, and that 

 towards the southern extremity of Lake Heron there is an extensive colony 

 of niggerhead, probably Carex secta, with tall and stout trunks. | 



** Swamp. 



On both sides of the so-called Lake Stream near where it issues from 

 Lake Heron, and in certain places near the margin of the lake itself, there 

 are extensive swamps which merge into bog and this into steppe. The 

 water-content varies much at different seasons of the year, as likewise at 

 times of heavy rain. Furthermore, their ecology has been much modified 

 by burning and the trampling of stock. 



Two principal subassociations were noted according to depth of the 

 surface water — viz., Schoenus pauciflorus (deepest water), Carex ternaria 

 (shallower water). 



At a distance the swamp appears of a uniform grey colour. It is 

 traversed by various streams, and pools of water lie permanently in many 

 places. A close view shows that the grasslike Carex Gaudichaudiana is the 

 most abundant plant. The two subassociations differ in colour, Schoenus 

 pauciflorus being reddish and Carex ternaria green. On the surface of pools 

 there is abundance of Ranunculus rivularis, which may quite hide the water. 

 Montia fontana, a species of Myriophyllum, and Epilobium macropus occur 

 more or less abundantly in the streams. Schizeilema nitens (creeping and 

 rooting slender-stemmed herb with small trifoliate shining glabrous leaves) 

 is abundant where water lies and the light is sufficient. 



Epilohium insulare, Carex diandra, C. stellulata, C. Oederi var. catar- 

 ractae, and Elaeocharis Cunninghamii are common on the very wet ground. 



As the soil gets drier Mazus radicans, its thin spotted yellowish leaves 

 flattened to the ground, is abundant, and both Carex ternaria and Schoenus 

 pauciflorus are absent. Drier soil still favours the presence of Pratia angu- 

 lata, and probably Isotoma fluviatilis, a creeping herb of similar growth- 

 form, is present. The following are other plants of the boggy ground : 

 Utricularia monanthos, Plantago triandra (rosette plant), Asperula perpusilla, 

 a species of Cotula, Viola Cunninghamii, Luzula species (flat, red leaves). 



Finally, Bulbinclla Hookeri var. angustifoJia (summer-green herb with 

 tuberous roots) is common both on wet and on dry ground, forming most 

 noticeable colonies when in bloom with its bright-yelloAv flowers, but it is 

 absent in the wettest part of the swamp. Also, this plant is extremely 

 common in wet ground throughout the montane and subalpine belts of the 

 district, and increases enormously after the vegetation is burnt. 



*** Sphagnum Bog. 



Only the bog connected with steppe is here dealt with ; that of the 

 forest climate, a)id which elsewhere in New Zealand is related to fell-field 

 and moor, Avas not examined. 



