DEVELOPMENT OF PLANTS 



451 



imally but one develops in the plum) and splits at maturity into 

 two valves, a form of fruit called a pod. For example, in the 

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

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

 lar 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 coffee 

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

 gularity becomes more noticeable in the sensitive pea (Cassia) 



Fig. 314. Flowers and fruits of the apple and plum families: A, inflor- 

 escence of the apple (Malus). B, section of flower, showing adhesion of 

 receptacle to the ovary, epigynous flower. C, sections of the fruit — c, car- 

 pels of the pistil; r, fleshy receptacle. D, flower of cherry (Prunus). E, 

 section of flower — r, cup-like receptacle which falls off as fruit matures. F, 

 fruit in section, showing the outer part of the wall of the ovary as a fleshy 

 rind and the inner part forming the stone or pit which enclosed a single seed. 



(Fig. 315, B-D). In the redbud, or Judas tree (Cercis), the 

 petals are ver}- irregular, two of them being insecurely united into 

 a boat-like structure, known as the keel, which encloses the ten 

 distinct 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 



