102 LABOHATORV STUDlJis OF TBI: FLOWJiB 



on the central axis of inflorescence; or tlie cluster goes on growing in 

 tlie main axis and putting out new flowers foi' a time, — so that the 

 lower flowers are older, tlie upper ones younger. The first type is 

 called determinate, or ci/ino.^e : the second, iiidelerminale, or racemose. 



Determine the type of inflorescence in the material furnished. 



Draw a diagram of the arrangement of the flowers, letting lines rep- 

 resent the stems, branches, and individual flower stalks (or pedicels). 

 and putting at the ends dots for the flowers, larger for tlie older, and 

 smaller for the 5-ouuger, flowers. 



Turn to the figures of the different sorts of cymose and racemose 

 inflorescences (page liO and following), and select the proper term 

 for the material in hand. 



Exercise XXXIV. The Flower of a Conifeuous Plant 



1. The Slamitiute Floiter 



Cut a longitudinal section. Xote the positions of the stamens. 

 Draw the outline of the whole flower (or cone) and the central axis, 

 and indicate the position and outlim- of two or three stamens. 



Detacli one stamen. Xote its general forni, and the number of 

 pollen sacs. I'o the sacs lie on the under or the up|ier side of the 

 stamen ? Fiml out about the jilaco where the sacs open for the emis- 

 sion of pollen. Draw one stamen, so as to show the pollen sacs 

 opened. 



Are there any scales or other structures answering to tlie perianth 

 of an angiospernious flower? 



Xote the size and niimlier of the pollen grains and examine with the 

 compound microscope if possible. 



2. The Pistillate Flower 



Before cutting into the flower (or cone), note the arrangement of 

 the scales. 



Note also the outstanding edges of the scales ; this feature is related 

 to the method of pollination. 



Draw a simple outline of the cone, and then indicate diagrammati- 

 cally the arrangement of the scales; that is. draw sinijile continuous 

 lines for the boundaries of the rows of scales. ^__^'an you see rows in 

 more than one direction V If so, draw the diagram accoi'dingly. 



Break the cone across. Separate one of the scales. On careful 

 examination it will be seen that the scale is double, so that there 

 seem to be two scales with a common base. The under one is tlie 

 smaller. The upper one is tlie placental scale, or orulifernus scale. 



Examine the upper surface of the placental scale titv two prnmi- 

 nences near Ihe base. Each has a few short filaniciils projpcling 

 toward the iixis of the cone. The prominences are the ovules. The 



