THE FLOWER OF THE HIGHER SEED-PLANTS 157 
a diagram for the cross-section of the flower of the white 
water-lily, of which a partial view of one side is shown in 
Fig. 115. 
Construct diagrams of the longitudinal section and the transverse 
section of several large flowers, following the method indicated in 
Figs. 114 and 116, but making the longitudinal section show the 
interior of the ovary.1 
It is found convenient in dia- 
grams of cross-sections to distin- 
guish the sepals from the petals 
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III 
Fic. 116. Diagram of Cross-Sections of Flowers. 
a 
I, columbine; II, Heath family; III, Iris family. In each diagram the dot 
alongside the main portion indicates a cross-section of the stem of the 
plant. In II every other stamen is more lightly shaded, because some 
plants of the Heath family have five and some ten stamens. 
by representing the former with midribs. The diagram- 
matic symbol for a stamen stands for a cross-section of the 
anther, and that for the pistil is a section of the ovary. 
If any part is lacking in the flower (as in the case of 
flowers which have some antherless filaments), the missing 
or abortive organ may be indicated by a dot. In the 
1 Among the many excellent early flowers for this purpose may be men- 
tioned trillium, bloodroot, dogtooth violet, marsh marigold, buttercup, tulip 
tree, horse-chestnut, Jeffersonia, May-apple, cherry, apple, tulip, daffodil, 
primrose, wild ginger, cranesbill, locust, bluebell. 
