206 FOUNDATIONS OF BOTANY 
Construct diagrams of the longitudinal section and the 
transverse section of several large flowers, following the 
method indicated in Figs. 155 and 157, but making 
° the longitudinal section show 
the interior of the ovary.) It 
is found convenient to distin- 
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gas 
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oe 
I II III 
Fig. 157. — Diagram of Cross-Sections of Flowers. 
I, columbine ; IJ, heath family ; III, iris family. In each diagram the dot along- 
side 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. 
guish the sepals from the petals by representing the 
former with midribs. The diagrammatic 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 diagram of the 
Iris Family (Fig. 157, III) the three dots inside the flower 
indicate the position of a second circle of stamens, found 
in most flowers of monocotyledons but not found in this 
family. 
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, crocus, tulip, 
daffodil, primrose, wild ginger, cranesbill, locust, bluebell. 
