W. Travers.—On the Spread of Cassinia leptophylla. 251 
vindicate the title of the native vegetation to the exclusive possession of the 
open lands which are used as natural pastures, or which have only been 
subjected to the ruder forms of cultivation. Amongst the causes which are 
probably leading to the present extension of this plant (independently of the 
facility which it enjoys, in common with other members of the Composite, for 
the dispersion of its seeds) are the increased production of fertile seeds, owing 
to the abundance of European bees all over the country ; the disturbance of 
the surface soil by the treading of animals; and possibly the destruction, or 
at all events a great diminution in numbers, of some form of insect life which 
formerly fed upon its flower-heads. In connection with the latter suggestion 
I may mention that it is extremely difficult to obtain mature seeds of many 
of the indigenous Composite. The flower-heads of the varies species of 
Celmisia, which are so abundant in the mountain districts of the South Island, 
for example, are usually attacked by a small Hemipterous insect, several 
individuals of which are generally to be found in each head. On one occasion 
I collected one hundred beads of Celmisia coriacea, the seeds of which, to out- 
ward appearance, were in good condition, but scarcely one of them contained a 
single sound seed, out of some eighty or a hundred which had been produced 
upon it, nearly the whole having been destroyed by the insects in question. 
But whatever the causes which are leading to the spread of the Cassinia 
may be, the fact and its evil consequences are certain, and it only remains to 
be considered what is best to be done under the circumstances. 
The first and most natural idea which occurs to the mind of the occupier 
of land thus invaded is, to endeavour to destroy the plant by fire, as is done 
in the case of other indigenous growths; but this has been found to be 
impossible, except where its growth is very dense, and not even then until 
it has attained several years of age. Оп small holdings, or where grass is 
specially valuable, it may pay to employ labour to eradicate it with the adze- 
hoe; but upon large or inferior runs the expense of such a process puts it out 
of the question. As the result of the enquiries which I made in Queen 
Charlotte Sound, I am led to believe that in the latter case it is best to let the 
plant take its course until it attains a growth sufficiently dense to admit of its 
being burnt. Iwas informed that it is usually ripe for this operation in about 
five years, and that after such a burning it does not re-appear, whilst the soil 
which it occupied has become better fitted for the growth of grass in 
consequence of its being opened out through the decomposition of the roots, 
We know that the thistle and the hawk-weed have both died out over immense 
tracts of country, owing, in all probability, to the exhaustion of some material 
necessary for their subsistence ; and I think it probable that the same cause 
will operate in the case of the Cassinia, even if its destruction be not 
precipitated by either of the processes above referred to. 
