202 
BRITISH FERNS. 
(oophoridia) ; those at the base of the inner ones having nume- 
rous minute oblong granules ( antheridia ) ; in both, the contents 
are seen to be, at least in an early stage, attached to delicate 
slender filaments .”- — Sir W. Hooker. 
The Isoetes or Quillwort family bear their capsules in 
the dilated base of their long awl-shaped leaves ; the 
capsules are of two kinds, like those in some species of 
Club-moss, — those situated in the outer leaves being of 
the bud-like order, and those in the inner leaves grain- 
like spores. 
The name is taken from two Greek words isos , equal, 
and etos , year, — signifying that the plant is the same all 
the year round. 
55. Isoetes lacustris, Linn. Quillwort, .or Merlin 5 s 
Grass. 
The Common Quillwort has erect, stout, cellular 
leaves ; roots 3 or 4 inches in 
length, sometimes branched, 
and nearly transparent ; these 
spring from the tuberous cau- 
dex, the crown of which bears 
the awl-shaped, brittle, ever- 
green leaves. 
The Common Quillwort 
grows at the bottom of moun- 
tain lakes, making a kind of 
submerged sward. It is found 
in subalpine situations in all 
parts of the United Kingdom. 
In the south of France, Sar- 
dinia, Sicily, and southern 
India, a species occurs with longer leaves, but Sir W. 
