PLANT WORLD CONTINUED 



227 



Fig. 123. Morphology of typical monoco- 

 tyledonous plant. A, leaf, parallel-ve ned ; B, 

 portion of stem, showing irregular distribu- 

 tion of vascular bundles ; C, ground plan of 

 flower (the parts in 3's) ; D, top view of 

 flower ; E, seed, showing monocotyledonous 

 embryo. (From C. Stuart Gager's "Funda- 

 mentals of Botany" by permission of- P. 

 Blakiston's Son & Co., Publishers.) 



Fig. 124. Morphology of a typical dico- 

 tyledonous plant. A, leaf, pinnately-netted 

 veined ; B, portion of stem, showing concen- 

 tric layers of wood ; C, ground-plan of flower 

 (the parts in 5's) ; D, perspective of flower; 

 E, longitudinal section of seed, showing dico- 

 tyledonous embryo. (From C. Stuart Gager's 

 "Fundamentals of Botany" by permission of 

 P. Blakiston's Son & So., Publishers.) 



outgrowth or pollen tube which penetrates the tissues surrounding the 

 egg and thus the sperm is carried to the egg, fertilizing it. 



Seed plants are commonly divided into 



Monocotyledons ( ) example, lilies, corn and 



grasses. (Fig. 123.) 



Dicotyledons ( ) example, beans and cotton. 



(Fig. 124.) 



The drawings of various stem cross sections will illustrate the dif- 

 erence in the structure of the two types of seed plants. (Fig. 125.) 



Angiosperms. In this type of plant the ovules are produced in a 

 closed ovary composed of one or more carpels ( ). 



The ovules become seeds, and the carpels and surrounding parts are 

 what constitute a fruit. This fruit may consist of the ripened ovary 

 only, or it may include the calyx ( ) and receptacle 



also. 



As no seed can be formed unless the reproductive organs, stamen 



