186 COMPOUND ORGANS OF PLANTS. 



Lastly, in the centre of the flower of the Claytonia, there 

 are three pistils ; two have therefore been suppressed. 



One or more entire verticils may have been wholly sup- 

 messed. We have already said that the complete flower 

 consists of four verticils of metamorphosed leaves, viz., the 

 calyx, corolla, stamens and pistils : now if any one of these 

 verticils be absent, the flower is incomplete. Deviations 

 resulting from the non-production of the verticils are not 

 uncommon, and may affect any of the floral organs. Thus the 

 calyx is reduced to an obscure ring or border in the holly and 

 dogwood, and is suppressed altogether in the prickly ash, 

 (Zanthoxyllum.) We infer that it is the corolla which remains 

 in this flower because the five stamens alternate with it. In 

 other instances the corolla is suppressed and the calyx remains 

 as in Anemone and Clematis. 



It is proper to remark here, that where there is only one 

 floral envelope, the law of alternation will enable us to detect 

 whether it is a calyx or a corolla. Thus if the corolla is sup- 

 pressed, it is easy to see that the two verticils between which 

 the corolla is developed will have their parts opposite, that is 

 to say, the androecium and the calyx. This is their natural posi- 

 tion, since the stamens alternating with the petals are necessa- 

 rily placed opposite to the sepals ; and therefore when we find 

 them in this position and only one floral envelope, we may con- 

 clude that envelope to be the calyx and the petals, to have been 

 suppressed, whatever may be its color and hue. If, on the 

 contrary, there is a single envelope with which the stamens 

 alternate, we may conclude that it is the calyx which has been 

 suppressed, and that the colored envelope is a true corolla. 

 This appears to be an easy way of settling this question where 

 other methods fail. 



