DEVELOPMENT OF PLANTS 



419 



honey locust (Gleditsia) and the Kentucky coffee bean (Gymno- 

 cladus), the receptacle forms a shallow- cup which bears the 

 regular sepals, petals and usually ten stamens about a single 

 pistil (Fig. 315, A). The flowers are really monoecious, but in 

 other respects are very suggestive of the plum flower. In the cof- 

 fee bean tree, however, the petals are not quite equal and this ir- 

 regularity becomes more noticeable in the sensitive pea (Cassia) 

 (Fig. 315, BD). In the redbud, or Judas tree (Cercis), the 

 petals are very irregular, two of them being united into a boat- 

 like structure and known as the keel which encloses the ten dis- 

 tinct stamens and single pistil, while two laterally placed petals, 

 the wings, inclose the fifth petal known as the standard (Fig. 315, 

 E, F). These three examples from the senna family make a 



FIG. 315. Development of the irregular type of flower in the rose order: 

 A, regular flower of the honey locust (Gleditsia). At left staminate 

 flower. At right pistillate with single pistil, c, which develops into long 

 flat pod, s, rudimentary stamens. B, flower of Cassia, showing slightly 

 irregular corolla. C, section of flower s, stamen ; c, pistil. D, the fruit 

 or pod. E, irregular flower of redbud (Cercis) c, calyx; k, keel en- 

 closing stamens and pistil ; w, wings which arch over the standard, s. 

 F, corolla removed, showing the ten stamens surrounding the simple pistil. 



