274 



REPRODUCTION OF HIGHER PLANTS 



III. Shake some pollen from the anther on to a glass slide. Mount under 

 the microscope. 



A. How many cells make up each pollen grain ? 



B. Describe the shape, color, and structure of pollen. 



C. Draw and label several pollen grains enlarged ten times. 



IV. Cut a thin cross section of the ovary of the pistil. Examine it with a 

 hand lens. 



A. The seedlike structures are the ovules. Note that the ovules are 

 attached to the ovary wall and are not loose in the ovary. The part of 

 the ovary wall to which the ovules are attached is called the placenta. 



V. Place an ovule on a glass slide. Cover it with a cover glass and crush it 

 by carefully pressing down with the cover glass. 



A. Does an ovule consist of one or more cells? 



Note a central structure. This is the embryo sac containing the egg 



B. 



cell. 

 C. 

 sac. 



Draw the outline of an ovule showing the position of the embryo 



Structure of the flower. The flower consists of a calyx made up 

 of sepals and a corolla made up of petals. While the essential 



organs 



)1S 



;til 



The essential organs for the reproduction of higher plants are the 

 stamens and pistils. Accessory organs are the sepals and petals. 

 The sepals enfold the entire flower, forming a bud. Thus the 

 organs are protected while they are ripening. The petals are fre- 

 quently showy and attract insects. This may result in pollination. 

 The stamens produce pollen and the pistil produces ovules. 



are rlpen•^ 

 ing, they are pro- 

 tected from rain, 

 insects, and certain 

 mechanical injuries 

 by the tightly en- 

 folding calyx and 

 corolla. The whole 

 ther IstxxmeTL structure com- 

 prises the bud. As 

 the essential organs 

 ripen, the calyx 

 and corolla unfold 

 and expose the 

 matured pistils and 

 stamens. 



st^le/ 

 ovarr^ 



amentj 

 ccl 



