METAMORPHOSIS. 



141 



very close to the Polycarpicae, having a perianth com- 

 posed of three whorls of two or three (often in Papaver 

 orient ah) members each, of which the two inner ones 

 are petaloid and the outermost is sepaloid. In the 

 Cruciferae the extra petals were subsequently added 

 by positive dedoublement of the two median petals of 

 the inner whorl. 



A rather remarkable form of sepalody occurs in the 

 double spurless variety of the columbine (Aquilegia 

 vulgaris var. stellata), in which the usually spurred 

 petals become replaced by spurless, flat, sepal-like 

 leaves.* Transitions have been observed, moreover, 

 between these two types of floral leaves. Both are 

 equally derived by metamorphosis of stamens, and this 

 affords another striking proof of the common origin, 

 viz., from the androecium, of both calyx and corolla. 



Celakovsky mentions that occasionally the two 

 outermost petals of the lesser celandine (Ranunculus 

 Ficaria) become transformed into sepals, so that a 

 5-merous calyx of normal orientation is thereby formed, 

 leaving five petals out of the original eight, and bring- 

 ing this plant in that respect into line with Ranunculus 

 acer, etc. In other cases extra petals were added from 

 the androecium to supply the place of those passed 

 outwards (PI. XLII, figs. 6 and 7). 



There are varieties of Iris Kxmjrferi and I. Sieboldii 

 in which the inner perianth-leaves or petals, instead of 

 being erect and of a different colour, are precisely 

 similar to the sepals in their colour, shape, and 

 position. 



C, de Candolle, as previously described, mentions 

 the appearance of an extra set of pappus-hairs in the 

 Edelweiss (Leontopodiuin alpinum) ; as he observed 

 transitions between extra corolla-lobes and pappus- 

 hairs, we must probably ascribe the phenomenon to 

 sepalody of the corolla ; but a most unusual and 

 remarkable case thereof. 



* But all but the five outermost members of the flower are best regarded 

 as petals. 



