CHAPTER IV 



THE FLOWER, FRUIT AND SEEDLING 



50. The Structure of the Flower. — -We now come to the most 

 interesting feature in the nature and Hfe of the plant. All the 

 energy of the plant is directed towards the perpetuation of its 

 kind. Numerous examples have been noted where this is ac- 

 complished by bulbs, rootstocks, buds, etc. Among our common 

 plants, however, new individuals are usually produced from seeds 

 that are formed in the flowers. We will first examine the struc- 

 ture of a flower and see how it is adapted to the performance of 

 this important work. A flower is a highly modified stem of the 

 bud type. This is very noticeable before the flower opens or is 

 in bloom (Fig. 74, A). A series of leaves usually of a greenish 

 color envelop the delicate parts within and protect them, as in the 

 case of the bud, against drying winds. These green leaves are 

 known as the calyx and each individual leaf is called a sepal. As 

 the bud opens a number of organs are disclosed, particularly 

 noticeable are a set of more delicate and variously colored leaves, 

 the corolla, each leaf of which is called a petal (Fig. 74, B). The 

 corolla is of service to the flower in many ways. Like the calyx 

 it may assist in protecting the other organs. Especially is it of 

 importance in guarding them against dews and rains. For this 

 reason the calyx and corolla, collectively called the floral envelop 

 or perianth, in many flowers often close at night or on rainy 

 days. It will be seen later in the work that the perianth is of 

 the greatest importance in assisting insects to visit the flowers 

 in such a way that seeds may be produced. Within the perianth 

 are two kinds of peculiar organs, the central flask-like ones are 

 called pistils or carpels and surrounding them are the stamens 

 (Fig. 74, B). These two kinds of organs are collectively known 

 as sporophylls since their special work is to produce certain 

 cells called spores. The sporophylls are the important organs 

 of the flower. The calyx and corolla may be lacking but no 

 seed can be formed without the sporophylls. 



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