102 LABORATORY STUDIES OF THE FLOWER 



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

 the main axis and putting out new flowers for a time, so that the 

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

 called determinate, or cymose ; the second, indeterminate, 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 the older, and 

 smaller for the younger, flowers. 



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

 inflorescences (page 140 and following), and select the proper term 

 for the material in hand. 



EXERCISE XXXIV. THE FLOWER OF A CONIFEROUS PLANT 



1. The Staminate Flower 



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

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

 and indicate the position and outline of two or three stamens. 



Detach one stamen. Note its general form, and the number of 

 pollen sacs. Do the sacs lie on the under or the upper side of the 

 stamen? Find out about the place 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 the perianth 

 of an angiospermous flower? 



Note the size and number 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 simple continuous 

 lines for the boundaries of the rows of scales. Can you see rows in 

 more than one direction ? If so, draw the diagram accordingly. 



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 the 

 smaller. The upper one is the placental scale, or ovuliferous scale. 



Examine the upper surface of the placental scale for two promi- 

 nences near the base. Each has a few short filaments projecting 

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



