THE DISPLACEMENT OF SPECIES IN NEW ZEALAND. 347 



and robust growth of the herb, which is not infrequently from 3 ft. 

 to 5 ft. in height above the water-level, and often impedes the 

 passage of boats. This luxuriance is chiefly due to the mildness of 

 the climate, and has a singular parallel in one locality in England. 

 At the Wyken 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 weather, the watercress is almost as luxuriant as in New 

 Zealand. The Canadian water-weed [Anacharis Alsmastnwi) simply 

 chokes the River 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 aquatic 

 plant that has become naturalized in the colony. 



Naturalized Fungi. 



Several naturalized fungi are highly injurious to the indigenous 

 vegetation, as the ergot {Clariceps purpurea), which infests numerous 

 native grasses ; the clematis cluster-cup ( /Ecidium clematidis) fre- 

 quently infests Clematis Culensoi and other species almost to the 

 point of destruction, the stem, petiole, and even parts of the flower 

 becoming thickened and distorted under its attacks : but the limits 

 of this address will not permit me to enter into detail. 



Rate of Increase. 



As the number of species more or less completely naturalized in 

 the colony is upwards of five hundred, it becomes a question of 

 some interest whether additions will be made to the catalogue at 

 the same rate during the next half-century as in the past ; if so, 

 the number of species of naturalized and indigenous Phanerogams 

 would be about equal, and many of the latter would be crowded out 

 of the field. A satisfactory answer may, I think, be given. 



The first catalogue of naturalized plants was published in the 

 original Flora of New Zealand, ii. 321 (1855). It comprises sixty- 

 one species, seventeen of which must be excluded as erroneous, 

 leaving forty-four naturalized species. The second list, published 

 in the Handbook of the New Zealand Flora, 757 (1867), contains 

 171, from which twenty-one species must be deducted as included 

 on insufficient grounds, leaving 150 species naturalized. A list 

 prepared by the present writer was published in Transactions of the 

 New Zealand Institute, ii. 131 (1869) ; it embodied all that was then 

 known on the subject, and enumerated 292 species, a summary of 

 which, given at p. 146, showed forty-one species erroneously in- 

 cluded, or of uncertain position, and 251 species truly naturalized. 

 During the three following years I added fifty-three species to the 

 list, making a total of 304 species known to me at the date of my 

 ceasing to reside in Auckland. In 1882 Mr. Cheeseman published 

 a list of the naturalized plants of the Auckland district, in which he 

 raised the total to 382 ; but this does not include a few species seen 

 by myself, and still unpublished. At the present time the number 



2 A 2 



