Flowers. 153 



d, F\ having them sustain the same relation to each other 

 as to overlapping as observed in the flower. 



In drawing the longitudinal diagram make first a faint 

 guide line, G, having the same relation to the vertical as 

 the axis of the flower has in its natural position on the 

 plant. The guide line is placed vertically in G, but in 

 violet, larkspur, Baptisia, etc., it would be at some angle 

 with the vertical. The position which the flower assumes 

 often has an important bearing on pollination. The mean- 

 ing of the irregularities of irregular flowers frequently can- 

 not be understood until the direction taken by the axis of 

 the flower is known. In the case of a flower having a 

 definite upper and under side, both the longitudinal and 

 the cross diagram should take note of this so that the 

 structurally under side of the diagram is directed toward 

 the bottom of the page and the upper side toward the top. 

 Space off on this guide line the relative lengths of ovary 

 and style, and on either side locate with points the greatest 

 diameter of the ovary, as shown in G. Then outline the' 

 pistil, as in H, and set points a and b to fix the relative 

 lengths of anther and filament, and points c, d, and e to 

 mark the height and greatest spread of the corolla and 

 calyx. At the base of the ovary continue the outline 

 upward to form the stamen, as in /, and continue the 

 outer line of the filament upward at the base to form the 

 petal, as in / and J t and continue in like manner to form 

 the sepal as in K. Construct the other half of the dia- 

 gram in the same manner. 



In outlining the cavities of the ovary, if the placentae 

 are central, draw first the inner border of the outer wall, 

 as in the right half of the pistil of diagram K, and then 

 continue this line to form the ovules, as in the left half. 

 If the placentae are parietal and there is more than one 



