THE PLANT GROUPS 



147 



(5) Summary. Summarize in terms of axis, perianth, 



sporophylls, and sporangia the similarities and 

 differences between the strobili of the spruce and 

 the flower you are examining. 



(6) Definition. Write a definition of a flower, consid- 



ering the above facts concerning its morphology. 



FIG. 25. The lily (Lilium philadelphicum) 



A, dissected flower, showing the pistil and stamens: p, parts of the perianth 

 which have been cut away; s, bases of stamens cut off. J5, floral diagram: 

 p, perianth, composed of two circles of similar and petal-like parts; s, stamens, 

 likewise in two circles ; section of ovule case (ovary) shown in the center, com- 

 posed of three carpels (c) so united as to form three locules containing the 

 ovules. From Bergen and Davis's "Principles of Botany" 



(7) Drawings. Draw a vertical long section of the 

 flower and label the parts with terms corre- 

 sponding to those used for strobili of Selaginella, 

 cycads, and spruce. Draw a ground plan of the 

 flower (Fig. 217 of text). 



