212 HISTORY OF BRITISH PERNS. 



The name comes from pilula, signifying a little pill, the 

 spore-cases having a nearly globular form. 



PILULARIA GLOBULIFERA, Linncem. The Pillwort, or 

 Pepper-grass. (Plate XYII. fig. 2.) 



Pepper-grass is a small creeping plant with grassy leaves, 

 growing usually in the shallow margins of lakes and pools, 

 where it is occasionally overflowed ; but sometimes occurring 

 entirely submerged. The stem, or caudex, is thread-like, 

 composed of several longitudinal rows of hollow cells, rough 

 externally on the younger portions with hair-like scales, but 

 otherwise smooth, occasionally branched, and producing on 

 the lower side at intervals of about half an inch, less or 

 more, small tufts of fibrous roots, which are slender, simple 

 or slightly branched, hollow, being divided longitudinally, 

 and descending almost perpendicularly into the soil in which 

 they become fixed. On the upper part of the stem, opposite 

 the tufts of roots, occur tufts of about a similar number of 

 erect leaves, which are curled up in the incipient state, like 

 those of a Pern, but on unrolling assume the erect position. 



These leaves are bristle- shaped, and of a bright green, 

 smooth externally, hollow within, but unlike those of Isoetes, 

 which are composed of four parallel lines of cells, the leaves 

 of the Pillwort are divided longitudinally into various cells, 



