THE DEVELOPMENT OF THE FLOWER 



387 



reduced archegonium. However, it is possible that all three of 

 the nuclei in the egg apparatus represent eggs, only one of 

 which is functional. 



While the embryo and endosperm are developing, the ovule 

 increases greatly in size, and its integuments change into the 



E D 



FIG. 310. Development of the flower of the shepherd's purse (Capsella) 



A, tip of stem, showing the origin of the flowers : s, first appearance of the sepals 

 in the flower /. B, sepals well along in their development and stamens st 

 appearing. C, later stage, showing the two young carpels c and the beginnings 

 of the petals p. D, later stage lettered as in the preceding. E, the petals now 

 well developed, and the ovules beginning to arise on the inner face of the 

 carpels, not yet united above to form the closed pistil 



seed coats. In some plants, as in the squash (Fig. 1), peas, and 

 beans, the embryo finally fills the entire seed, and the endo- 

 sperm is almost completely crowded out, being represented by a 

 thin membrane around the embryo. In other forms, as the corn 

 (Fig. 3), asparagus, and poppy (Fig. 4), the embryos remain small, 

 and the endosperm is conspicuous as a tissue richly stored with, 

 food material. 



