Ill] POLYSTELY 37 



Gwynne-Vaughan^. The rhizomes contain an indescribable con- 

 fusion of bundles, which he suggests may have been derived 

 from a simpler structure previously existent in a stem with 

 longer internodes; the adoption of a rhizomic habit, associated 

 with telescoping of the internodes, might well lead to this 

 extreme complexity. The most interesting anatomical feature 

 of the family, however, is the occurrence of polystely. In the 

 rhizome of Victoria regia 

 " all the root-bearing 

 bundles belonging to 

 the same leaf-base are 

 grouped together so as to 

 form a structure having 

 the appearance of a defi- 

 nite and distinct stele," 

 in which about twenty 

 bundles form a ring. 

 However the most typi- 

 cal polystely occurs, not 

 in the rhizomes them- 

 selves, but in the elon- 

 gated tuber-bearing stolons, which certain species of Castalia 

 produce as lateral branches. In the stolons of Castalia flava^ 

 for instance, the bundles are arranged in four or five widely 

 separated groups or steles, each enclosed in an endodermis 

 and surrounding a protoxylem canal. In Cabomba, on the other 

 hand, it is the rhizome in which polystely occurs, though in 

 the simplest possible form; two steles occur throughout, each 

 consisting of a single pair of bundles. The significance of 

 polystely in aquatic plants will be considered in Chapter xiii. 



The Nymphaeaceae have a remarkably well-developed aerating 

 system in their leaf- and flower-stalks. The long peduncles of 

 Waterlily flowers are said to have been sold in the bazaars at 

 Cairo as tobacco pipes: the base of the flower, which was 



1 Gwynne-Vaughan, D. T. (1897); see also Trecul, A. (1845) and 

 (i854),Wigand, A. (1871}, Blenk, P. (i 884), Strasburger,E. (1884), etc. 



Fig. 19. Castalia Lotus, Tra.tt. {Nymphaea Lotus, 

 L.) var. monstrosa. Germination in spring of a 

 tuber which has developed in place of a flower ; ?i , 

 simple first leaf . (Reduced.) [Barber, C. A. (1889).] 



