LABORATOEY STUDIES OF THE FLOWER 



101 



Exercise XXXII. 



The Parts of the Flower in Relation 

 TO One Another 



Cut a new flower neatly in halves lengthwise. 



Draw the half flower as seen from the cut side, to show : — 



(1) the shape of the pistil; 



(2) the relative positions and heights of the other parts. 



The summit of the flower stem, generally somewhat enlarged, from 

 which the organs spring, is the receptacle. 



Looking down upon or into the flower, endwise, make out the rela- 

 tive position of the sepals, petals, stamens, and cells of the ovary. 



When these have been made out definitely, make a diagram of the 

 flower as seen from above, in the following manner : — 

 1st. Represent the ovary in cross section. 



In a circle — if so found in the flower — around the ovary, 

 roughly indicate the cross sections of the anthers, properly 

 placed as regards direction from the ovary cells. 

 Represent petals by arcs of a 

 circle, properly placed ; the 

 arcs may be thickened a 

 little at the middle to repre- 

 sent midribs of the petals. 

 Outside these draw similar 

 figures for the sepals, in 

 the proper places with 

 respect to the other parts. 



2d. 



3d. 



4th. 



The 



diagram thus constructed 



shows the ground plan of the flower. 

 The annexed figure shows the method 

 of constructing such diagrams. 



In case any two parts of the 

 flower are grown togethei*, as two 

 petals, or a petal and a sepal, as 

 sometimes happens, this fact may 

 easily be indicated in the diagram 

 by drawing a dotted line between 

 the conjoined members. 



129 a. Flower and floral diagram 

 of Trillium. 



Exercise XXXIIT. The Arrangement of the Flowers on 

 THE Stem or Stems : or Inflorescen^ce 



When flowers come in clusters they are found in one of two differ- 

 ent types of inflorescence. Either a flower, early produced, ends the 

 main stem of the cluster, so that no further growth of the cluster in 

 the line of the axis is possible ; in this case new flowers are produced 

 only on side branches, and these side flowers are younger than that 



