MOEPHOLOGY OF EEPEODUCTIVE OEGANS 135 



2. Addition or Multiplication of Parts. — This may be con- 

 sidered under two heads. 1st. The addition of one or more 

 entire whorls in one or more of the floral cycles. 2nd. An in- 

 crease in the number of parts of one or more whorls. The 

 former is commonly called augmentation, the latter chorisis, 

 deduplication, or unliuiiig. 



a. Augmentation. — The increase in the number of whorls 

 may occur in one or more of the floral cycles. Thus the Bar- 

 berry {fig. 249) has two whorls of sepals, two of petals, and two 

 of stamens ; in this flower, therefore, we have an addition of one 

 whorl of members to each of the three external floral cycles. In 

 the Poppy, we have a number of additional whorls of stamens 

 {fig. 250). 



The increase in the number of the whorls is most common 

 among the stamens. Very frequently there is one extra whorl 

 intercalated here, so that the stamens are twice as numerous as 

 the sepals or petals. So constant is this occurrence in Mono- 

 cotyledons that many botanists regard two whorls of stamens 

 as a normal feature of that group. Such flowers are said to be 



Fig. 249. 



Fig. 250. 



Fig. 251. 



Fig. 249. Diagram of the flower of tlie Barberry {Berberis). Fig. 250. 



Diagram of tlie flower of tlie Poppy (Fapticer). Fig. 251. Diagram of 



the flower of Budcthorn (Jihamnus catharltciis). 



diplostemonous, in contradistinction from those with one whorl 

 which are called isostemonous. 



The new whorl generally falls into spnmetrical position with 

 the others, being alternate with the outer stamens on the one 

 side and the carpels on the other. Sometimes, as in Geraniaoes, 

 this alternation is not observed, and of the two whorls of sta- 

 mens the outer is opposite to the petals. This condition is 

 known as obdiplostemony. In such a flower the departure from 

 typical symmetry, due to multiplication, is complicated by a 

 further one of displacement. 



A curious arrangement of augmented stamens is found in 



