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A TEXTBOOK OF THEORETICAL BOTANY 



The suppression of a petal, like the posterior 

 petal in Koelreiiteria, has an obvious effect. 

 (2) The fusion of equal parts, especially 

 members of the perianth, into unequal groups. 

 This seldom occurs in the absence of other 

 irregularities, an exception being the two- 

 lipped corolla of Lonicera (see Fig. 1244). (3) 

 Lateral displacement of parts, not associated 

 with fusions or other irregularities, hardly ever 

 occurs, as might be deduced from the general 

 principle of equidistance. The appearance of 

 such displacement, creating a superficial or posi- 

 tional zygomorphy, may arise from the lateral 

 bending of mature parts, which are symmetrically inserted, as in the corolla 

 of Rhododendron (Fig. 1067) and Dictamnus (Fig. 1068). (4) By far the most 



Fig 



1066. — Floral diagram of 

 Vihurtiinn. Only one carpel 

 of three is fertile. 



Fig. 1067. — Positional zygomorphy of the 

 corolla in Rhododendron. 



Fig. 1068. — Positional zygomorphy of the 

 corolla in Dictamnus fraxi?ulla. A visit- 

 ing bee is seen below. 



