THE COROLLA. 29 



12. The curtain or volva, is the membranous covering 

 of the fungus tribe, concealing their parts of fructifica- 

 tion, and in due time bursting ail round, forming a ring 

 upon the stalk. 



Such is the original meaning of this term, as explained hy Linnaeus ; 

 but it is row used to signify the fleshy external covering of some 

 other fungi, which are scarcely raised out of the ground, and enfolds 

 the whole plant when young. It is well exemplified in the common 

 mushroom, &c. (F. 35.) 



THE COROLLA. 



13. The corolla is the interior envelope of the flower, 

 investing the central parts, but invested by the calyx. 

 (F. 10, cc.) It is generally of a finer and much more 

 delicate texture than the calyx, and is, of all parts of the 

 fructification, the most showy and ornamental, being al- 

 ways, or with but few exceptions, that which is the most 

 highly coloured, and hence commonly regarded as alone 

 constituting the flower. 



The yellow part, which you were directed to remove in the fourth 

 note, constituted the corolla of the primrose : or if you take the tulip 

 you will readily know the corolla, because there is never any calyx 

 to that flower. 



14. All that it is necessary to observe here of the co- 

 rolla is, that the leaves (F. 3,) of which it is composed are 

 called petals, to distinguish them from the other leaves 

 of the plant, and from the divisions of the calyx. 



In some instances, it is a very difficult pointof investigation,to dis- 

 tinguish the corolla from the calyx, for nature has not always distin- 

 guished the organs in question by any very obvious or decisive cha- 

 racter. The calyx is, indeed, generally green, and the corolla coloured, 



