b ELEMENTS OF STRUCTURAL BOTANY. 



flower. If you look at a flower which is a little older, 

 you will probably not find any sepals. They will have 

 fallen off, and for this reason they are said to be deeidii- 

 ous. So, in like manner, the leaves of most of our 

 trees are deciduous, because they fall at the approach of 

 winter. You will find that you can pull off the sepals 

 one at a time, without disturbing those that remain. 

 This shows that they are not connected together. They 

 are therefore said to be free, and the calyx is described 

 as 2Jolysepalous. 



Inside the circle of sepals there is another circle oi 

 leaves, usually five in number, bright yellow in colour, 

 and much larger than the sepals. Each of them is 

 called a petal, and the five together form the corolla of 

 the flower. Observe carefully that each petal is not in- 

 serted in front of a sepal, but in front of the space be- 

 tween two sepals. The petals can be removed one at a 

 time like the sepals. They, too, are free, and the cor- 

 olla is poh/jictdlous. If you compare the petals with one 

 another, you will see that they are, as nearly as possi- 

 ble, alike in size and shape. The corolla is therefore 

 regular. 



6. We have now examined, minutely enough for our 

 present purpose, the calyx and corolla. Though their 

 divisions are not coloured green, li];c the ordinary leaves 

 of the plant, still, from their general form, you will have 

 no difiiculty in accepting the statement that the sepals 

 and petals are in reality leaves. It will not be quite so 

 apparent that the parts of the flower which still remain 

 are also only modifications of the same structure. But 

 there is good evidence that this is the case. Let us, 



