Some of the inside petals are small with an anther at the tip.
Of course flowers do not go through all these changes every time they bloom now. They used to way, way back, when things were in a general state of change, but after awhile they found out just how to do it, and so out of the tiny buds at once made pistils and stamens and petals and sepals.
For sepals, too, came from stamens. The plants made all these new forms out of the materials of their leaf buds and wrapped them all together into a flower bud; so when this opened, there were the parts all ready to go to work without any more shifting around.
The calyx was ready to protect, the corolla to call the bees and butterflies, the stamens to make pollen, the pistils to make ovules.
Sometimes flowers forget and go back to the old ways of doing things; and if we are lucky enough to find such a flower, we can see just how it happened.
Sometimes roses behave in this peculiar way, and the flower goes back to leaves.
I used to know a bush whose roses did that. The pistils were leafy and also the stamens, and sometimes a branch grew right out of the middle of a rose as it does out of a leaf bud. Of course it was a very ugly-looking thing, neither flower nor leaf, but it was very instructive.
What do you suppose double flowers are?
Very often they are only flowers whose stamens have changed into petals.
A double rose has fewer stamens than a single rose, and sometimes all the stamens are changed, and the rose has not a grain of pollen to help itself with. What becomes of its seeds? It does not have any, as a rule. Where flowers become very double, the vitality goes to make petals instead of essential organs, as stamens and pistils are called, and such flowers often set no seeds.