3C4 ORGANOGRAPHY. 



organs of a whorl. We shall treat this subject briefly under 

 these two heads. 



a. Suppression or abortion of one or more whorls. — We have 

 already stated, that a complete flower is one which contains 

 calyx, corolla, stamens, and pistil. When a whorl is su])pressed 

 therefore, the flower necessarily becomes incomplete. This sup- 

 pression may either take place in the floral envelopes, or in the 

 essential organs. 



Sometimes one whorl of the floral envelopes is suppressed, as 

 in Chenopodium (Jig. 425), in which case tlie flower is upetalous 

 or monoclilamydeous ; sometimes both whorls are suppressed, as 

 in Euphorbia (Jig. 497) and common Ash (^fig. 426), when the 

 flower is termed naked or achhinu/deous. 



When a wliorl of the essential orj^ans is suppressed, the flower 

 is imperfect, as it then cannot by itself form seed. The stamens or 

 the pistil may be thus suppressed, in both of which cases the 

 flower is unisexual. When both stamens and pistil are sup- 

 pressed, as in certain florets of some of the Conipositae, &c., the 

 flower is neuter. When the stamens arc abortive, the flower is 

 termed pistillate ; or when the pistil is absent, staminate. The 

 terms moncecious, dioecious, and polygamous, which have reference 

 to this point, have been already sufficiently explained. Some 

 botanists, as already noticed (p. 361), consider that when the 

 organs of adjacent whorls are opposite to each other instead of 

 alternate, that such an arrangement of parts arises from the 

 suppression of an intermediate whorl ; but this view is mani- 

 festly insuflScient to account for such a circumstance in all cases. 

 Thus in the RhamnacejE (Jig. 771), the stamens are opposite to 

 the petals, and frequently united to them at the base, and we 

 cannot but regard them as produced by transverse chorisis from 

 the petals. In some cases, therefore, we regard the opposition 

 of the parts of contiguous whorls to be due to suppression, and 

 in others to chorisis. 



b. Suppression of one or more organs of a whorl. — This is a 

 very common cause of deviation from normal structure; we can 

 here only bring forward a i(i\\' examples. 



This suppression of parts is most frequent in the gynoecium. 

 Thus in the Crucifcnv (Jig. 772), we have four sepals, four 

 petals, six stamens, and two carpels; here two carjK'ls are sup- 

 pressed: in the Heart's-ease (Jig. 775), we have a pentamerous 

 flower, so far as the calyx, corolla, and stamens are concerned, 

 but only three carpels, two carpels being sui)pre>sed: in many 

 Leguminous Plants (Jig. 776), we have five se])als, five jjctals, 

 ten stamens, and only one carpel, four of the latter being here 

 abortive: in plants of tlie order Composittv (Jigs. 952 and 954), 

 the calyx, corolla, and andrcecium, have each five organs, but 

 only one, or, acc'ordiii<x to other botanists, two carpels. 



In sonic sjiecies of Jmpaticns (Jig. Ill), we have five carpels, 



