152 BOTANY 
The great function of the sepals is to protect, 
especially while in the bud, the interior parts of the 
flower, not only from the attacks of inseets but from 
excessive evaporation, as well as cold and rain. The 
importance of the ealyx, as a protection against 
extreme cold, is often well seen in the spring. If, after 
some of the flower buds have opened on the fruit 
trees, there comes a cold snap, it will be found that 
the flowers in which the calyx has expanded, will, in 
most cases, drop off the trees; while those that were 
still protected by the sepals remain unharmed and 
form fruit in the ordinary way. If there appears to 
be danger of a late frost, fruit growers will often 
build smoky fires in their orchards to check radiation 
of heat, and thus save the opening buds. During the 
winter of 1910 the author was investigating certain 
peculiarities of the flower buds of the ixerba (tawart), 
a beautiful tree found in the northern parts of New 
Zealand, and especially plentiful on Te Aroha moun- 
tain. In the course of the investigation, it was neces- 
sary, about mid-winter, to remove the sepals from a 
number of these buds, which, though they are well 
formed by the end of May, do not usually expand till 
November. For three weeks after this mutilation the 
weather was mild and fine, and the petals began to 
show signs of unfolding. At this stage, however, there 
was a whole week of rain, at the end of which it was 
found that the petals were beginning to decompose. 
The decomposition was soon communicated to the 
stamens and pistil, and, as a result, the whole flower 
was rendered useless. In some eases, especially where 
petals are absent, as in the clematis and anemone, the 
calyx becomes petaloid or petal-like, and, by attracting 
insects, does the work of petals. 
The petals and sepals together form the perianth 
while the petals alone constitute the corolla. While in 
a measure protective, the petals are eoneerned mainly 
