298 THE STRUCTURE OF FLOWERS. 



This has been observed in Anemone nemorosa, cultivated 

 varieties of Ranunculus, Violet, and Gentiana Amarella. 



Retrogressive Metamorphoses of Stamens. — For the 

 stamens to become petaloid, it is extremely common, as in 

 double flowers, and such a change may represent what 

 is normally the case in Water-lilies, Canna, and Atragene 

 (Fig. 44, p. 141). Changes may apply to the anther lobes, 

 connective, or filament, or to all together. Fuoiisias often 

 bear filaments with petaloid expansions of the apex, at the 

 base of which are one or two anthers showing varying 

 degrees of degeneration. This is a very similar condition to 

 one in Petunia, described by Dr. Masters, in which the con- 

 nective had developed into a green roundish blade bearing 

 two anther cells at the base (Fig. 81).* In such cases, it 

 seems to be the connective which has expanded outwards 

 and become the blade of the petal or leaf. Similarly, in the 



Fig. 81. — Foliaceous connective of Petunia Fig. 82. — Petalody, or "liose-in-hose'Torm, 

 (after Masters). of counectives in a double Columbine. 



double Columbine petalody of the connective sometimes takes 

 place (Fig. 82). f Commelina alba has also furnished a case 

 of an anther lobe becoming petaloid. 



Causes of " Doubling." — There can be no doubt that 

 petalody results from a weakened reproductive energy, espe- 

 cially that of the androecium, which can become constitu- 

 tional and may be hereditary and transmissible by crossing. 

 * rerafo?o<7j/, p. 254. ^ Ihid., p. 293 



