ORGANS OF FLOWERING PLANTS 21 
(b) Petals (Figs. 5-7). Fixed on the base of the 
ealyx tube are the petals which collectively form the 
corolla. At the back is the broad standard, at the 
sides the wings, and in front, more or less enclosed by 
the wings, the two united petals that form the keel. 
This arrangement of the petals is peculiar to the bean, 
pea, and other members of this family. In the wall- 
flower and buttercup the petals are all of the same 
form and the corolla is therefore symmetrical. The 
chief function of the corolla is to render the flower 
visible from a distance, so that insects may see and 
visit it. These insects carry from the stamens of one 
flower to the earpels of another the yellow, dust-like 
pollen, without which no fruit can be formed. In the 
tutu a well known native tree the petals become fleshy 
and succulent, and by this modification help to form 
the fruit. 
(c) Stamens (Figs. 6-8). In the bean, these lie 
inside the keel and appear as ten fine threads, nine 
united for some distance from the base to form 
an imperfect kind of tube, and one quite free. 
At the end of each slender thread or filament 
is a little knob, the anther, which contains the 
pollen. The stamen is the male organ of the 
flower, and the pollen its essential part. Hach 
earpel or collection of carpels must receive some of 
this pollen or it will not develop into a fruit. The 
pollen is better seen in such flowers as the lily, iris or 
narcissus. The arrangement of stamens found in the 
bean flower is peculiar to that family. In the manuka 
or tea-tree, the buttercup and poppy, the filaments are 
free throughout their entire length. While still domg 
their own work, stamens may be modified to perform 
other functions. It is to the brightly coloured stamens 
alone that the rata owes the erimson blaze that 
