OF THE ORGANS. 



93. 



In a polypetalous corolla, the smaller part of the petals, 

 which often resembles a stalk, is called the nail {unguis)^ 

 and the expanded part is called lamina, (^8.) When the 

 ungues stand thick together, they also form a tube, the en- 

 trance to which, in like manner, is called the throat. The 

 scales, which in some of these plants protect the entrance, 

 constitute the corona faucis, as in Silene. 



94. 



The corolla is often arranged in several rows ; we have thus 

 an interior and exterior corolla {corolla interna et externa), 

 as in the Contortae, particularly Eustegia, in Sauvagesia, and, 

 as some think, in the Grasses. What in these last has been 

 called, in the Linnaean acceptation, the^Corolla, is only an ex- 

 terior cover, which, in contradistinction to the gluma calycina, 

 is named gluma corollina. It is divided, like the former, in- 

 to valves (valvce), of which there are commonly two : they 

 have been lately called stragula, and the valves paleas. 

 Within this gluma corollina, there are found, in most of the 

 Grasses, but not in all of them, two very small, delicate, and 

 transparent leaflets, resembling often a tuft of hairs, and 

 springing immediately from the sexual parts. These seem 

 to form the true corolla. Linnaeus called them, falsely, nee- 

 taria. They have also been called lodicula ; (Tab. Ill, 

 Fig. 7.), (101.) 



95. . 



We must also pay some attention to the regularity or irre- 

 gularity of the corolla. . ^ 



It is impossible to ^Ve technical names to the infinitely 

 varied forms which here present themselves. The general 

 varieties of form have also been already noticed (31. 32.), so 

 that we need only to apply them to the corolla. We shall, 

 therefore, notice only at present the distinct forms of the ir- 

 regular corolla. 



Of these the simplest is, undoubtedly, the tongue-shaped 

 (corolla ligulata), which, in the Aristolochiae, changes into 



