150 



ELEMENTS OE BOTANY. 



through the flower lengthwise, like those of Pig. 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. 135.^ 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 



KIG. 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 

 tile calyx, around the pistil ; III, 

 corolla hypogynous, stamens epi- 

 petalous. 



Fig. 134, — Wliite Water-Lily. The 

 inner petals and the stamens grow- 

 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. 

 134.2 



Construct diagrams of the longitudinal section and the 

 transverse section of several large flowers, following the 



1 For floral diagrams see Thomi's Botany, Le Maout and Decaisne's Traiti 

 Giniral de Botaniqiic, or Eichler's BlUtheHiliaijramme. 



2 It is best to begin practice on floral diagrams with flowers so firm and large that 

 actual sections of them may be cut Avith ease and the relations of the parts in the 

 section readily made out. The tulip is admirably adapted for this purpose. 



