260 



THE FLOWKR. 



that an outer circle is suppressed.* For since the calyx is fre- 

 quently deUcate and petal-like (in botanical language petaloid or 



colored), and the corolla sometimes greenish 

 or leaf-like, the only real difference between 

 the two is, that the calyx represents the 

 outer, and the corolla the inner series ; and 

 even this distinction becomes nioi-e or less 

 arbitraiy when either, or both, of these or- 

 gans consist of more than one circle. The 

 apparent obliteration of the calyx in some 

 cases is owing to the entire cohesion of the 

 tube with the ovary, and the reduction of the free portion, or limb, 

 to an obscure ring or border, either slightly toothed or entire, as in 

 Aralia (Fig. 410), Fedia (Fig. 882), Cornus, the fertile flowers of 

 Nyssa, &c. In Compositic, the partially obliterated limb of the 

 calyx, when present at all, consists of scales, teeth, bristles, or a 

 ring of slender hairs (as in the Thistle), and receives the name of 

 pappus. 



481. The petals, however, are frequently absent ; when the flower 

 is said to be apetalous, as in the Anemone (Fig. 411), Clematis, 

 Caltha, &c., in the Crowfoot family, 

 other genera of which are furnished 

 ■with both calyx and corolla ; and as 

 in some species of Buckthorn, while 

 others have manifest although small 

 petals. They are constantly wanting 

 in a large number of families of Ex- 

 ogenous plants, which on this account 

 form the division Apetalce. When 

 the calyx is present while the corolla 

 is wanting, the flower is said to be 



monochlamydeous, that is, with a perianth (417) or floral enveloj)e of 

 only one kind ; as in the cases above mentioned. 



* In our Northern Zanthoxylum the monoclilamydeous perianth which is 

 present may, however, be justly held to be the corolla, and not the calyx, be- 

 cause the five stamens alternate with it, just- as they do with the undoubted 

 petals of Z. Carolinianum : in this case, therefore, we may say tliat tlic calyx, 

 and not the corolla, is suppressed. See Genera Illustrata, Vol. 2, p. 148, tab. 1.56. 



FIG. 410. Flower of Aralia nudicaulis, vertically divided ; the limb of the calyx obsolete. 

 FIG. 411. Flower of Anenioue Pennsylvanica j apetalous, the calyx petaloid. 



