86 ELEMENTS OF STRUCTURAL BOTANY. 



and is then described as 2xq)pose. In other cases the 

 hmb is quite inconspicuous, and so is said to be obsolete. 

 A calyx which remains after the corolla has disappeared, 

 as in Mallow (Fig. 31), is persistent. If it disappears 

 when the flower opens, as in our Bloodroot, it is cadu- 

 cous, and if it falls away with the corolla, it is deciduous. 



We must repeat here, that when calyx and corolla are 

 not both present, the circle which is present is con- 

 sidered to be the calyx, whether green or not. 



129. The Corolla. The calyx and corolla, taken 

 together, are called the Jioml envelopes. "When both 

 envelopes are present, the corolla is the inner one ; it 

 is usually, though not invariably, of some other colour 

 than green. Each division of a corolla is called a jietal, 

 and the corolla is polijpetalous when the petals are com- 

 pletely disconnected ; but (janiupetalous if they are 

 imited in any degree, however slight. The terms 

 regular and irregular, applied to the calyx, are applica- 

 able also to the corolla, and the terms used in the 



description of leaves are applicable to 

 petals. If, however, a petal is narrowed 

 into a long and slender portion towards 

 the base, that portion is known as the 

 elau, whilst the broader upper part is 

 Fig. 138. called the liwh (Fig. 138). The leaf- 

 terms are then applicable to the limb. 



130. Gamopetalous corollas assume various forms, 

 most of which are described by terms easily understood. 

 The forms assumed depend almost entirely on the 

 shape of the petals which, when united, make up the 

 corolla. If these, taken separately, are linear, and are 



