262 



THE FLOWER. 



tenth (the posterior) stamen is distinct or nearly so (Fig. 320). But 



in Amorpha (Fig. 323, 

 324), which belongs to the 

 same family, an approach 

 to regularity is seen in this 

 respect, the ten stamens 

 being united barely at their 

 base ; and there is a com- 

 plete return to regularity 

 in those of Baptisia (Fig. 

 322), which are perfectly 

 distinct or separate. An 

 example of a different 

 sort of irregular blossom is 

 afforded by the Fumitory 

 Family, the structure of 



which has already been explained, especially as to the stamens 

 (455, Fig. 296). The floral envelopes of Dicentra are in one view 

 regular, inasmuch as the two members of each circle are alike : 

 but the exterior pair of petals is very unlike the interior pair ; and 

 in Corydalis and Fumaria itself one of the exterior petals is unlike 

 the other, rendering the blossom more conspicuously and truly 

 irregular. Here the irregularity is combined with more or less 

 cohesion of the petals ; although this union, like that of the two 

 keel-petals of a papilionaceous flower, is not congenital, but occurs 

 subsequently to the development of the organs. 



469. There are many other forms of irregular polypetalous 

 blossoms, which we cannot here separately explain, such as that of 

 Polygala, and that of the Larkspur and Monkshood, both of which 

 are farther complicated by the suppression of some organs, as well 

 as by the irregular development of others. 



470. Among gamopetalous flowers the most common case of 

 irregularity is that of what are called bilabiate (or two-lipped) co- 

 rollas, which prevail in the Mint Family, and to some extent in 

 several related families. Here the irregularity of form does not 

 arise from the suppression of some of the petals, as might at first 



FIG. 321. Papilionaceous flower of Baptisia. 322. The same, with the petals removed, 

 showing the ten distinct stamens. 



FIG. 323. Flower of Amorpha. 324. The same, with the solitary petal removed, showing 

 the slightly monadelphous stamens. 



