126 PRINCIPf.ES OF PLANT'TEEATOLOGY. 



The changes which each type of floral leaf undergoes 

 will now be considered. 



(1) Calyx. 



Phyllody. — This includes those cases in which sepals 

 become foliaceous. 



The change may be very slight; in some flowers of 

 Clematis viticella some of the white petaloid sepals were 

 slightly virescent near the apex ; other sepals were 

 green throughout, except along the two basal margins. 

 In some of the sepals the change was complete to a 

 ternate foliage-leaf. In another species {C. Fortunei) 

 the change was not nearly so complete, the leaves being 

 " simple." 



In the tulip the three sepals have been observed quite 

 green, as they normally are in the Commelynaceae. 



In some flowers of Primula sinensis the upper surface 

 only of the enlarged sepals was virescent. In some 

 other flowers of this plant received from Mr. Odell 

 the calyx had become foliaceous, although in most of 

 them the sepals remained united into a tube below; 

 here and there, however, a sepal was quite foliaceous, 

 having a long petiole ; in all these cases the zygo- 

 morphism of the calyx was much more marked than 

 in the normal flowers, and the posterior sepal larger 

 than the rest. The polyanthus {P. vulgaris var.) often 

 shows a leafy calyx (PI. XL VII, figs. 1-5). 



In the rose it is frequent for the sepals to be con- 

 genitally transformed into well-developed foliage- 

 leaves. Transitional forms show that the normal sepal 

 does not correspond to the leaf -base, but to the entire 

 leaf. PL XLII, fig. 1, shows a flower, similarly trans- 

 formed, of a lacitiiate variety of the blackberry {Rubus 

 fruticosus) ; in correlation with this remarkable change, 

 the corolla has become completely suppressed. 



In Heleniitm autumnale and the goat's-beard (Trago- 

 pogonpratense), belonging to the Compositse, the pappus 

 (calyx) of the florets has been seen changed, in the 



