54 
HISTORY OF BRITISH FERNS. 
III. PEPPERWORTS == MABSILEA CEAE. 
Flowerless plants, bearing axillary or radical spore - 
cases, haring many cells. They comprise the genera 
Isoetes and Pilularia. 
22. Isoetes — Stemless, quill-leaved, water plants, with 
the fructifications enclosed within the swollen bases 
of the leaves. 
23. Pilularia = Creeping, slender-leaved, water plants, 
with the fructifications in globular, sessile, four- 
celled spore-cases. 
IY. HORSETAILS = EQ UISETA CEJE. 
Flowerless plants , with spore-cases attached beneath pel¬ 
tate scales, which are arranged in terminal cones. 
This group consists of the genus Equisetum. 
24. Equisetum = Jointed, tubular-stemmed plants, with 
terminal cones of fructification. 
