ISOETES. 235 



submerged grass, that the inexperienced eye would pro- 

 bably pass it by unnoticed. It has a fleshy tuber, of a 

 nearly globular form, white, and of compact texture in- 

 ternally, but spongy and of a dark-brown colour externally. 

 In the centre is a small nearly pellucid part, which 

 appears to be the growing-point, since it is from this 

 point that the leaves have their origin. From these 

 tubers are produced the long semipellucid tubular roots, 

 which strike downwards almost perpendicularly. The 

 leaves spring from the crown of the tuber, and grow erect 

 to the height of four or six inches, or more. They are 

 persistent, and of an olive-green colour, and their general 

 form is awl-shaped. The basal portion is dilated and 

 furnished with membranous margins ; above this dilated 

 base they are bluntly quadrangular, being formed of four 

 parallel hollow tubes, which tubes are subdivided at irre- 

 gular distances by transverse partitions, while towards the 

 apex they taper off and terminate in a sharp point. The 

 transverse partitions above mentioned, being visible through 

 the texture of the leaf, give it a jointed appearance. 

 Owing to their brittleness, they not unfrequently break off 

 at one of these joint-like points, their basal parts and the 

 decaying remains of the older leaves continuing to encircle 



