150 ELEMENTS OF BOTANY. 
through the flower lengthwise, like those of Fig. 133, help 
greatly in giving an accurate idea of the relative position of 
the floral organs. Still more important in this way are 
cross-sections, which may be recorded in diagrams like those 
of Fig. 185.1 In constructing such diagrams it will often be 
necessary to suppose some of the parts of the flower to be 
raised or lowered from their true position, so as to bring 
iE II it 
FIG. 133.— Insertion of the Floral 
Organs. 
I, Hypogynous, all the other parts 
on the receptacle, beneath the 
pistil; II, Perigynous, petals and 
stamens apparently growing out of 
the calyx, around the pistil; IJ, Fic. 134.— White Water-Lily. The 
corolla hypogynous, stamens epi- inner petals and the stamens grow- 
petalous. ing from the ovary. 
them into such relations that all could be cut by a single 
section. This would, for instance, be necessary in making a 
diagram for the cross-section of the flower of the white 
water-lily, of which a longitudinal section is shown in Fig. 
134.? 
Construct diagrams of the longitudinal section and the 
transverse section of several large flowers, following the 
1For floral diagrams see Thomé’s Botany, Le Maout and Decaisne’s Traité 
Général de Botanique, or Eichler’s Bliithendiagramme. 
2 It is best to begin practice on floral diagrams with flowers so firm and large that 
actual sections of them may be cut with ease and the relations of the parts in the 
section readily made out. The tulip is admirably adapted for this purpose. 
