POLYMOEPHY. 329 



instances of fasciation, i. e. where several branches are 

 fused together and flattened, we must admit that this 

 flattening does not occur very often as a teratological 

 appearance. 



Mr. Rennie figures and describes a root of a tree 

 which had become greatly flattened in its passage 

 between the stones at the bottom of a stream, and had 

 become, as it were, moulded to the stones with which 

 it came into contact.^ 



The spadix of Arum, as also of the cocoa-nut palm, 

 has been observed flattened out, apparently without 

 increase in the number of organs. 



When the blade of the leaf is suppressed it often 

 happens that the stalk of the leaf is flattened, as it 

 were, by compensation, and the petiole has then much 

 the appearance of a flat ribbon (phyllode). This 

 happens constantly in certain species of Acacia, Oxalis, 

 &c., and has been attributed, but doubtless erroneously, 

 to the fusion of the leaflets in an early state of develop- 

 ment and in the position of rest.^ 



In some water plants, as Sagittarla, Alisma, Pota- 

 mogeton, &c., the leaf-stalks are apt to get flattened out 

 into ribbon-like bodies; and Olivier has figured and 

 described a Cyclamen, called by him C. llneanfolium, 

 in which, owing to the suppression of the lamina, the 

 petiole had become dilated into a ribbon-like expan- 

 sion deformation rubanee of Moquin. 



CHAPTER II. 



POLYMORPHY. 



Usually the several organs of the same individual 

 plant do not differ to any great extent one from another. 

 One adult leaf has nearly the same appearance and 



' . Loudon's ' Magazine Nat. Hist.,' vol. ii, p. 463. 



C. Morren, ' BuU. Acad. Belg.,' 1852, t. xix, part iii, p. U4,. 



