THE FLOWER 



209 



ovules and seeds. Draw the ovary in cross and vertical 

 sections, labeling correctly all the parts. 



229. The numerical plan of dicotyls. — Diagram the plan 

 of the flower in cross and vertical section. How many parts 

 are there in each set ? Can you tell readily 

 the number of stamens ? When the indi- 

 viduals of any set or cycle of organs are too 

 numerous to be easily counted, like the 

 stamens of the apple, pear, and peach, or 

 the petals of the water lily, they are said 

 to be indefinite. It is very seldom that per- 

 fect symmetry is found in all parts of the 

 flower. The stamens and pistil, in partic- 

 ular, show a great tendency to variation, so 

 that the numerical plan is generally deter- 

 mined by the calyx and corolla. Where the 

 parts are in fives, as in the pear, quince, and wild rose, the 

 flower is said to be pentamerous, or in sets of five. This is the 

 prevailing number among dicotyls, though other orders are 



Fig. 301. — VertP 

 cal section of an al* 

 mond blossom with 

 petals removed, show- 

 ing the perigynoua 

 arrangement. 



302 



W.i 



304 



Figs. 302-304. — Diagrams showing arrangement of parts with reference to the 

 ovary: bd, receptacle; A-, calyx ; A:/-, corolla; st, stamens; fr, ovary; g, style; n, 

 stigma ; 302, perigynous ; 303, hypogynous ; 304, epigynous. 



not uncommon. In the mustard family (220) and other 

 well-known species, the fourfold order prevails, while some 

 of the saxifrages have their parts in twos, and the magnolia 

 and the pawpaw have a threefold arrangement. 



