If we guessed five we should guess just right. There is no doubt but that once upon a time the plants from which our morning-glories are descended had five separate petals. The morning-glories themselves manage it differently now, but it took them a long time to do it. They were working away, long before the great pyramids of Egypt were built, to get their five petals united into one piece. But it is done, and they have learned how to twist the flower up tightly in the bud and then unroll it in all its glory.

They never have five petals now, but they still bear traces of it.

Look at the little notch on the border, halfway between two nectar guides. Does that tell us anything?

Count the notches. Five, you see.

Look at the line that runs from the notch down to the bottom of the flower.

The corolla looks as though it had been folded along those lines. You can easily see five long creases ending in a notch. The flower is folded along these lines in the bud, but we think the lines have yet another meaning.

Carefully tear the corolla down the lines; you see, a very little pressure does it. Now we have the corolla in five parts, like five petals, only it is so weak it can no longer hold itself up. Once upon a time we think it grew this way, with five separate petals, only the petals stood up then, for they must have been stiffer and perhaps were not so long. It was long, long ago, oh, very long ago, that it had its five petals. Then the edges of the petals began to grow together, and they kept on doing this until, in course of time, the whole length of each petal had grown fast to the next one, all except that little tiny spot where the notch is.

We are glad our morning-glory kept this little notch and the line where the sides of the petals grew together, for that is what tells us the story of long, long ago when all the petals were separate.

When finally they were grown together, the corolla did not need to be so stiff, for its shape helped to make it firm, and then it no longer used good material to make stiffening for the petals, for that would have been a waste of plant sap, and plants do not like to waste materials. When they find they can get along without something they have been used to having, they stop making it. Life is too short and too precious to waste a bit of it. Our flower only kept the stiffening in the corolla along the paths where it wished the bees to go to its honey cups and where, when folded, it could best protect the bud.