OF TENDRILS. 271 



frequently have a tendency to twist spirally as true 

 tendrils. 



Corollas themselves, notwithstanding their fugacity, 

 sometimes take the appearance of a tendril; thus, in 

 the genus Strophanthus the lobes of the corolla are 

 prolonged into a fine filament, from one to tw T o inches 

 long in most of the species, and even attaining seven 

 inches in S. hispidus of Sierra Leone : the five filaments 

 proceeding from the five lobes are twisted together 

 before the expansion of the flower, thus forming a kind 

 of floral tendril which twines around the neighbouring 

 branches. The tops of the anthers of Nerium Oleander 

 are prolonged into kinds of apparently corolline ten- 

 drils, which are sometimes twisted together, as those of 

 Strophanthus. Thus all the organs capable of changing 

 into spines appear endowed, in other plants, with the 

 faculty of changing into tendrils. 



Stems put on this appearance in a great number of 

 cases ; and it is usual to call them simply by the name 

 of twining or climbing stems. The annual shoots are 

 the parts which most frequently present this tendency ; 

 whence it results, that when the plant is an annual, it is 

 twining throughout its whole life. In perennial plants, 

 two cases happen : — the stem either constantly remains in 

 the same twisted state as it was in during the first year, 

 as in most Passion-flowers ; or, the lower part becomes 

 so firm as to be able to support itself, and then we have 

 a shrub with an erect stem and twining branches ; this 

 is observed in several species of Convolvulus. The 

 reverse takes place, according to Vaucher, in Periploca 

 Grceca, which scarcely twines the first year, but after- 

 wards very strongly encircles trees which it meets with. 



The ti'ansformation of organs into spines supposes in 

 general the existence of a hard and solid fibrous tissue ; 

 therefore this texture is more or less remarkable in all 



