150 NEW ZEALAND PLANTS. 
occupies large areas of the lowland and montane belts where the 
silver-tussock (Poa caespitosa) has been repeatedly burnt. Where 
tussock still persists, danthonia (one or other variety of Danthonia 
pilosa) occupies the ground between the tussocks. 
Few plants in the world possess greater powers of aggression, 
even against well-equipped competitors, than this indigenous New 
Zealand grass. For example, the primeval forest of the Ruahine- 
Cook Botanical District, growing on rather poor soil, has been felled, 
the fallen trees burnt, and an orthodox grass-seed mixture of various 
European grasses and clovers has been sown. This has led in a brief 
time (partly through the heavy fertilizing of the ground by wood- 
ashes) to the establishment of excellent pasture, on which sheep are 
grazed. For a few years this pasture holds, but by degrees danthonia 
enters in, and it is only a short time before it easily becomes the 
dominant grass. 
Equally striking but more sensational has been, in Central Otago, 
the effect of burning the tussock, overstocking with sheep, and 
allowing the rabbit to take possession in its millions. For miles the 
tussock is gone; so, too, have the other grasses and herbs. Gazing 
at the scene from one or other of the river-valleys—say, the Clutha 
near Cromwell—the mountains look like huge sandhills; at a 
distance there is no evident sign of plant-life. But a closer view 
shows this not to be the case. The ground, its surface no longer 
protected by the tussocks, covered with stones, scarred and carved 
by rain, is dotted everywhere with silvery patches of two raoulias 
—-Raoulia lutescens and R. Beauverdu. These denizens of stony 
river-bed, thanks to the suitability of their freely produced seed for 
carriage by the wind, have speedily taken advantage of the situation 
and seized on the new ground. Nor would the attempt be a new 
one. For thousands of years their seeds must have flown on to the 
tussock-grassland in hope (speaking of the plants as though they 
were endowed with reason) of finding a nursery for the young plants ; 
but the hope was vain—the competition with the well-equipped 
members of the primitive formation was too keen. So, too, the 
little grass Poa maniototo is there in its thousands, and an indi- 
genous annual or biennial chickweed, Stellaria gracilenta. It is, 
however, certain foreign plants rather than the indigenous ones which 
can tolerate and perhaps enjoy the new conditions. Thus sorrel 
(Rumex Acetosella) is extremely common even where rabbits are 
