T. KiKK. — Displacement of Sj^ecies in New Zealand. 23 



only naturiilised species capable of injuring pasturage to any- 

 serious extent, and, unhappily, it is often the cause of serious 

 loss to the pastoralist and agriculturist. The Gundagai thistle, 

 as it is called in New Zealand (Carddius pycnocepkahis, Jacq.), 

 flourishes on newly-disturbed soil in many localities, but is 

 comparatively rare on grass-laud. 



Whenever the finely-comminuted basaltic scoria of the 

 Auckland isthmus is disturbed, a luxuriant crop, chiefly of 

 naturalised plants, speedily makes its appearance, but amongst 

 them one of the most abundant is the indigenous Ghenopodimn 

 carinahmi (E. Br.), although not a specimen may have been 

 seen in the vicinity until the surface was disturbed. After the 

 second year the number of plants is greatly diminished, and 

 during the fourth year only solitary specimens are to be found. 

 A similar instance has been observed at Cape Whanbrow, 

 near Oamaru. Whenever the fine silt which covers the sur- 

 face is disturbed, LepuUuvi tenuicaiLle (T. Kirk) and the indi- 

 genous form of Atriplex patula (L.) make their appearance in 

 abundance, although usually both plants are only to be found 

 in small quantity. 



Naturalised Aquatic Plants. 



The increase of the watercress [Nasturtium amiphibium, 

 E. Br.) in streams and watery places is phenomerial, and 

 attracts the attention of new arrivals on account of the 

 excessive luxuriance and robust growth of the herb, which 

 is not infrequently from 3ft. to oft. in height above the vvater- 

 level, and often impedes the passage of boats. This luxuri- 

 ance is chiefly due to the mildness of the climate, and has 

 a singular parallel in one locality in England. At the VVyken 

 Colliery the water pumped up from a great depth is of a high 

 temperature, and flows into a stream which expands into a 

 large, shallow pond. As the pond is never frozen, even in the 

 severest weatlier, the watercress is almost as luxuriant as in 

 New Zealand. 



The Canadian water-weed [Anacliaris ahinastruin, Bab.) 

 simply chokes the Eiver Avon at Christchurch, and has been 

 carried by aquatic birds to other streams in Canterbury and 

 Otago, but is rare in the North Island, being restricted, so far 

 as known to me, to a river near Mongonui, and another in 

 the Bay of Plenty. It is of considerable interest, owing to its 

 being the only submerged a:][uatic plant that has become 

 naturalised in the colony. 



Naturalised Fungi. 

 Several naturalised fungi are highly injurious to the indi- 

 genous vegetation, as the ergot [Claviceps purpurea, Tub), 

 which infests numerous native grasses ; the clematis cluster- 



