MODIFICATIONS OF THE FLORAL ORGANS. 177 



one stamen which has been split into two by collateral chorisis, 

 thus producing the want of symmetry in the stamineal circle. 

 And that this supposition has some foundation is evident from 

 what we see in Streptanthus hyacinthoides, (Fig. 76,) one of the 

 wild flowers of Texas. In this plant the chorization has been 

 arrested before its completion, so that in the place of two 

 stamens we see a forked filament bearing two anthers. 



The beautiful marsh flower, called by botanists the ElodaBa 

 Virginica, (Fig. 77,) furnishes us with another sample of col- 

 lateral chorisis. The ground plan of this flower, a, shows it to 

 be both pentamerous and trimerous in its organization, its 

 floral envelopes consisting of five sepals and petals, whilst its 

 androecium and gymnoecium consist of nine stamens and three 

 pistils, the nine stamens being triadelphous, and evidently 

 formed by collateral chorization out of three, as shown at b. 

 The three glands which occupy an intermediate position 

 between the corolla and the androecium, as shown in the dia- 

 gram, are probably the rudimentary traces of an exterior circle 

 of stamens which have been rendered abortive. 



Fig. 78. Fig. 79. Fig. 80. 



Transverse chorization, or the separation of a lamina from 

 organs already formed, is believed to take place in the case of 



16 



