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or less coherent, along the lower margin, forming a boatlike 

 space on their upper surface, in which He the essential 

 organs of the flower. These two lower petals are together 

 called the keel. The petals are all yellow, more or less 

 marked with purple-brown. This arrangement of the 

 corolla gives to Peaflowers their peculiar appearance, which 

 to some vivid imagination has recalled the idea of a butter- 

 fly. As the scientific name of a genus of typical butter- 

 flies is Papilio, so botanists commonly call Peaflowers 

 papilionaceous, and give to the family the name of 

 Papilionaceee. 



A thing that should be noted is that the petals are not 

 attached, as in Heath, to the top of the flower-stalk, but to 

 the inner surface of the calyx tube. The insertion is so 

 close down that this is not very noticeable, but it is the 

 commencement of the removal of the corolla from the 

 top of the stalk that develops further in Roses, Saxifrage, 

 and many other families, to culminate in the Myrtles and 

 Umbellifers. It is a matter of first importance in the 

 sorting together of different families of flowers. 



The stamens are ten in number. Each consists of a 

 slender filament and a two-chambered anther. They are 

 inserted in a calyx tube close to the base of the petals. 

 The stamens are all free from one another. This is a con- 

 dition that marks a section of shrubbv Peaflowers, far 

 more common in the Southern than in the Northern 

 Hemisphere. Other sections which are also represented 

 in Australia have the filaments united for part of their 

 length in a tube, which may be entire or open above, or 

 the nine lower filaments are united, but the upper one free- 



The pistil of a Peaflower is very simple. It consists of 

 a single carpel, which develops few or more ovules. The 

 pistil in the flowering stage is always slender. It lies in 

 the centre of the stamens, in the cavity of the keel. From 

 the end of the ovarian cavity it is prolonged in a slender 

 style, which bends upwards towards the tip, so that the 

 small terminal stigma comes to lie amongst the anthers 

 at the end of the keel. 



Comparison with other plants and study of malforma- 

 tions has led to the conclusion that a carpel is a modified 

 leaf, and usually bears the ovules on its margin. This is 

 easy to examine in a Peaflower, as no complication is 

 introduced by the blending of many carpels. The carpel is 

 a leaf which in our flower is bent together lengthwise, so 

 that the margins meet together and the ovules hang down 

 into the ovarian chamber from above. 



