GROUP V. ANGIOSPERM.E. 



447 



are antipetalous. This is not, however, a case of direct super- 

 position, since the corolla intervenes between the androecium and 

 the calyx, and the androecium intervenes between the gynseceum 

 and the corolla. 



There are, however, certain cases in which this law of alter- 

 nation does not prevail, in which, that is, the members of 

 successive whorls are directly superposed. Tor instance, the (4-5) 

 stamens are directly antipetalous in several natural orders 

 (Primulacese, Plumbaginaceae, Ampelidaceae, Rhamnaceae) ; again, 

 in some Campanulacese (e.g. Campanula Medium, Fig. 263) the (5) 

 carpels are directly superposed on the stamens. 



The Floral Diagram. These various arrangements of the floral 

 leaves, like those of the foliage-leaves, are most clearly represented 



FIG. 262. Floral diagram (ground-plan) 

 of an acyclic flower, with \ divergence in 

 the calyx, corolla, and androeciam (ter- 

 minal flower of Berberis : after Eichler). 



Fio. 263. Floral diagram of Cam- 

 panula Medium : the five carpels are 

 directly superposed on the stamens. 

 (After Eichler). 



by means of diagrams (see p. 13). In & floral diagram, the calyx 

 lies externally, and the gynseceum, as being the uppermost series 

 of organs (even in epigyhous flowers) lies most internally. In order 

 to be able readily to distinguish the various series, symbols are 

 used which recall some peculiarity of their form : thus the mid-rib 

 of the sepals is indicated, and, in the case of the stamens, the 

 anthers. 



If only such relations of position as can be actually observed in 

 a flower are indicated in the diagram, a simple empirical diagram 

 is the result. If, however, the results of the investigation of the 

 development of the flower and of the comparison of it with others 

 be borne in mind, a general plan of arrangement will be detected, 

 and the individual peculiarities of arrangement, quite apart from 

 any variation in the form of the organs, will be seen to be due 

 either to the suppression of one or more whorls or of one or more 



