ITS VARIOUS MODIFICATIONS. 239 



as well as stamens and pistils (41 6) ; symmetrical, having an equal 

 number of parts in the successive whorls (436) ; regular, in having 

 the different members of each circle all alike in size and shape ; it 

 has but one circle of the same kind of organs ; and, moreover, all the 

 parts are distinct or unconnected, so as to exhibit their separate 

 origin from the axis or receptacle of the flower. This type may be 

 presented under either of the four numerical forms which have been 

 illustrated. That is, its circles may consist of parts in twos (when 

 it is binary or dimerous), threes (ternary or trimerous), fours {qua- 

 ternary or tetramerous), or fives (quinary or pentamerous). The 

 first of these is the least common ; the trimerous and the pentame- 

 rous far the most so. The last is restricted to Dicotyledonous plants, 

 where five is the prevailing number ; while the trimerous flower 

 largely prevails in Monocotyledonous plants, although by no means 

 wanting in the Dicotyledonous class, from which Fig. 353 is taken. 



447. The principal deviations from the perfectly normal or 

 pattern flower may be classified as follows. They arise, either 

 from, — 



1st. The production of additional circles of one or more of the 

 floral organs (regular multiplication or augmentation) ; 



2d. The production of a pair or a cluster of organs where there 

 should normally be but one, that is, the multiplication of an organ 

 by division (abnormal multiplication, also termed deduplication or 

 chorisis) ; 



3d. The anteposition (or opposition, instead of alternation) of the 

 parts of successive circles ; 



4th. The union of the members of the same circle (coalescence) ; 



5th. The union of adjacent parts of different circles (adnation) ; 



6th. The unequal growth or unequal union of different parts of 

 the same circle (irregularity) ; or, 



7th. The non-production or abortion of some parts of a circle, or 

 of one or more complete circles (suppression or abortion). 



8th. To which may be added, the abnormal development of the 

 receptacle or axis of the flower. 



448. Some of these deviations interfere with the symmetrical 

 structure of the flower ; others merely render it irregular, or dis- 

 guise the real origin or the real number of parts. These deviations, 

 moreover, are seldom single ; but two, three, or more of the kinds fre- 

 quently co-exist, so as to realize almost every conceivable variation. 



449. Several of these kinds of deviation may often be observed 



