XXX IV 



MORPHOLOGY OF FLOWER 



467 



assumption of a petaloid form by the outer stamens, various 

 intermediate stages being present from the typical stamen, 

 through irregular leaves with anther-lobes at their distal ends, 

 to the ordinary broad white petal. 



We see, then, that a stamen is a leaf on the surface ol 

 which four microsporangia (b^, ;///. s/>g) are developed : the 

 blade of the leaf is narrowed to form a mere stalk, whi1'> the 



Fig. 125.— a'-a*, transition from petal to stamen : mi. sf>g, micro- 

 sporangia ; Jl, filament ; an, anther. 



B^, transverse section of male sporophyll in the stage A^ ; tin; mid- 

 rib of staminal leaf; mi. spg, microsporangia. 



b'^, transverse section of typical anther, showing connective (cor) with 

 vascular bundle or midrib (mr), on the left two microsporangia (mi. 

 spg), and on the right the escape of the microspores [mi. sp) by dehis- 

 cence of the anther. 



microsporangia have become so closely aggregated as to 

 form a single four-lobed body, the anther (b-). 



Similarly the carpel can be shown to conform to the leaf- 

 type. The flower of the cherry has a single flask-shaped 

 carpel, consisting of a rounded venter, with an expanded 

 stigma borne on the end of a stalk or style. But when the 

 cherry flower becomes double, the normal carpel is replaced 

 by a little green leaf, quite like a foliage-leaf, except that it 

 is permanently folded upon the midrib so as to bring the 

 two halves of its upper or dorsal surface almost into contact 



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