132 ELEMENTS OF STRUCTURAL BOTANY. 



are entirely distinct from each other, the calyx is poly- 

 sepalous; if they are united in any degree, it is gamo- 

 sepalous. A calyx is regular or irregular according as the 

 petals are of the same or different shape and size. 



206. In a gamosepalous calyx, if the sepals are not 

 united to the very top, the free portions are known as 

 calyx-teeth, or, taken collectively, as the limb of the calyx. 

 The united portion, especially if long, as in Willow-herb, 

 is called the calyx-tube, and the entrance to the tube its 

 throat. In many plants, particularly those of the Com- 

 posite Family, the limb of the calyx consists merely of a 

 circle of bristles or soft hairs, and is then described as 

 pappose. In other cases the limb 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 caducous; 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 considered 

 to be the calyx, whether green or not. 



207. The Corolla. The calyx and corolla, taken 

 together, are called the floral 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 petal, and the 

 corolla is polypetalous when the petals are completely 

 disconnected ; but gamopetalous if they are united in any 

 degree, however slight. The terms regular and irregular, 

 applied to the calyx, are applicable also to the corolla, and 

 Uifl terms used in the description of leaves are applicable 



