FLOWER AND FRUIT 185 
again some of the seeds may fall in situations more 
favourable to their development than that occupied 
by the parent plant. Moreover, when well distributed, 
the seeds get away from the shade of the plant that 
bore them and into new soil that has not been 
exhausted of the particular minerals they need, and at 
the same time crowding of the seedlings is obviated. 
In short, where seeds are widely seattered there are 
numerous possibilities. Many may fall in places 
altogether unsuitable for their development, but there 
is always the chance that one or more - among 
thousands may light on the ideal environment and 
become the progenitors of a long line of stalwart 
descendants. Plants, then, which have an efficient 
means of seed dispersal have a considerable advantage 
in the struggle for existence. 
Wind, water, and animals are the chief agents of 
seed distribution, though fruits themselves may pos- 
sess mechanisms which independently serve the same 
purpose. 
1. Wind is the chief agent (Fig. 121). Many seeds 
such as those of orchids, being very small and dust- 
like, may be carried great distances by the wind. The 
dandelion fruit, as well as the fruit of many of the 
senecios so plentiful in New Zealand, are distributed 
by the assistance of a modified calyx which forms a 
pappus or tuft of hairs that greatly increases their 
buoyancy. In the willow and kaiku (Parsonsia) the 
tuft of hair is on the seed which escapes from the fruit. 
The fruit of the ake-ake, ash, and elm have mem- 
branous wings that also provide for wind distribution. 
The feathery style of the clematis serves the same 
purpose. In the silvery sand-grass (Spintfex hirsutus) 
the whole inflorescence may, in its season, be seen 
tumbling along the beach, for this is its way of 
distributing its seed. 
