THE FLOWER. 81 



theless a comparison of the flower of a given species as we 

 actually find it, is, as a rule, readily made with 



- , . . Modifications, 



tlie assumed type, and this comparison is a 

 necessaiy part of the morphological study of any flower. 

 In carrying out such a study it is found that flowers 

 may vary from the type in any one (or in more than one) 

 of its characteristic features. In the first place, 



i r ,1 11- T < i Coalescence, 



members ot the same whorl, instead 01 being 

 separate, may be more or less completely united. The 

 calyx of the primrose, the bell-shaped corolla of the cam- 

 panula, the united filaments of various members of the 

 pea family, and the compound ovary of the lily, are 

 familiar examples. Coalescence of parts is held by bota- 

 nists to indicate a higher development than has been 

 attained by flowers in which the parts remain free. 



A still further step in the same direction is seen in the 

 union of contiguous parts of different circles. Thus the 

 flower of the Fuchsia has the calyx-tube so 



, . , , . Adnation, 



united with the ovary as to make it appear as if 

 inserted on its summit, and both petals and stamens are 

 inserted on the calyx, the filaments showing very plainly 

 their union with the calyx-tube. The various degrees of 

 adnation furnish important characters that are constantly 

 employed in descriptive botany. 1 



Again, while the typical flower is regular, having all the 

 parts of a given whorl alike in size and shape, the flowers 

 of the more highly developed species, as a rule, 



T i j 1 -4- rpi -, n Irregularity. 



show marked irregularity. Ihe spurred corolla 

 of the violet, and the curiously irregular flowers of the 

 sweet pea, salvia, and snapdragon are striking cases. It is 

 believed that these are descendants of much simpler forms 



1 Cf. Gray, Structural Botany, pp. 182-184. 



