VIIl] 



PERIANTH : PERIGONE 



69 



peculiarities, that it becomes necessary to distinguish this 

 type of floral envelopes as a Perianth. Perianth (or 

 Perigone) is used by some writers to denote all the floral 

 envelopes present : in this case the perianth of a Lily is 

 a homochlamydeous perianth, as opposed to the hetero- 

 chlamydeous perianth in which calyx and corolla are well 

 differentiated. In the cases mentioned above the perianth 

 is iDetaloid, since the parts resemble petals ; but in other 

 cases e.g. Rushes (Junctis), Luzida, Nettles, Elms, &c. 

 the perianth is sepaloid, since the parts resemble sepals 

 more than they do petals. 



Fig. 22. A and B, inferior toothed calyx of Vine ; C, gamosepalous 

 tubular calyx of Guelder Eose ; D, epigynous calyx-tube, bearing five 

 sepals, of Gooseberry ; E and F, almost obsolete, epigynous calyx of Ivy. 



It remains to add that the apetalous condition may 

 be brought about by abortion of the petals, as is well 

 seen in Clematis and in some genera of Caryophyllaceae 

 e.g. Gerastium, where a whole series of forms can be found 



