COALKSCKNCE OF ITS PARTS. 249 



out. But this arises from the symmetrical augmentation of each set 

 of organs into two circles, which in the expanded flower appear like 

 one. In the flower-bud of the Barberry the calyx is seen to consist 

 of two alternating circles of sepals, three in each ; the corolla, of two 

 circles of petals, three in each ; the three exterior petals alternating 

 as they should with the inner circle of sepals, and the three interior 

 ones alternating with these. But when the flower opens, the six 

 petals, spreading apparently as one whorl, are necessarily opposed 

 to the six sepals ; and the six stamens in two circles, which are still 

 more confluent into one whorl, are equally opposed to these, taken six 

 and six ; although they really alternate in circles of three. In other 

 words, decussating verticils of threes necessarily form six vertical 

 ranks (251, 441). It is just the same in the Lily, Crocus, and most 

 Monocotyledonous plants ; where the perianth is composed of six 

 similar leaves in two circles, and the androccium of six stamens in 

 two circles, giving a regular alternation in threes ; although, when 

 taken by the casual observer as composed of two circles of six, it 

 gives the appearance of six stamens before as many petals. 



462. The Coalescence or union of the parts of the same whorl or 

 set of organs is so frequent,, that few cases are to be found in which 

 it does not occur, to a greater or less extent, in some portion of the 

 flower. When the sepals are thus united into a cup or tube, the 

 calyx is said to be monosepcdous, or, more correctly, gamosepalous ; 

 when the petals are united, the corolla is said to be monopetulous, or 

 yamopetalous. The latter is the appropriate term, as it denotes 

 that the petals are combined ; but the former is in common use, al- 

 though etymologically incorrect, as implying that the corolla consists 

 of a single petal. The current names, in these cases, were given 

 long before the; structure was rightly understood. So, also, such a 

 calyx or coiolla is said to be- entire, when the sepals or petals are 

 united to their very summits ; or to be toothed, lobed, cleft, or parted, 

 according to the degree in which the union is incomplete ; this lan- 

 guage being employed just as in the case of the division of leaves 

 (281). On the other hand, when the sepals are not united, the calyx 

 is said to be polysepalous ; and when the petals are distinct, the 

 corolla is said to be polypetalous ; that is, composed of several 

 petals. 



463. The union of the stamens with each other may occur either 

 by their filaments, as in the Pea and most of the Pulse family, or by 

 their anthers, as in the Sunflower and the whole Composite family, or 



