APPENDAGES OF THE COROLLA AND PETALS. 239 
The corolla is usually composed of but one whorl of petals, 
and it is then termed simple ; but in some flowers there are two 
or more whorls, as in the White Water-lily (jig. 453, p), in which 
case it is called multiple. When the corolla is composed of but 
Fie. 500. 
Fic. 498. Fie. 499. ~~~: 
Fig. 498. Petal of a Crowfoot with a nectariferous scale at its base.—/ig. 
499. One of the petals of Mignonette ( Reseda ).-—~Fig. 500. A petal of the 
Grass of Parnassus (Parnassia palustris) bearing afringed scale at its base. 
one whorl, its parts in a regular arrangement alternate with the 
sepals, although cases sometimes occur in which they are opposite 
to them. The cause of these different arrangements will be 
explained hereafter, under the head of the Symmetry of the 
Flower. 
Fic. 501. Fie. 502. 
ety 
Fig. 501. A petal of a species of Zychnis. 0. Claw. i. Limb. a. Scaly ap- 
pendages.— Fig. 502. Flower of the Daffodil ( Varcissus Pseudo-narcissus). 
The cup or bell-shaped process towards the centre is termed a corona. 
On the inner surface of the petals of many flowers we may 
frequently observe appendages of different kinds in the form of 
scales or hair-like processes of various natures. These are com- 
