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THE BRITISH PEPPERWORTS. 
The group of plants to which the name of Pepperworts 
has been given, is technically called Marsileacece^ and 
contains but a few genera, these being of very curious 
structure. It has only two representatives in the British 
flora. These two plants belong to different genera, and 
are both submerged aquatic plants of small size, agreeing 
in having grassy or quill-like foliage, but differing mate- 
rially in habit, the one being of creeping habit and the 
other tufted. The fructification also presents some mate- 
rial differences, on which account Isoetes is sometimes 
classed with the Club-mosses, instead of the Pepperworts. 
Genus XXII. ISOETES, or QUILLWORT. 
Isoetes, which takes its name from the Greek words isos, 
equal, and etos, the year, on account of its retaining its 
