Isoetes . ] 
FERNS. 
73 
ISOETES, Linn. QUILLWORT. 
(From «ro(;, equal, and erog, the year ; the plant being evergreen.) 
PLATE OF GENERA, FIG. XVIII. 
A, lower part of a plant of Isoetes lacustris, half the natural size. B, portion 
of the filiform leaf \ magnified. C, receptacle of the larger kind of spore. D, 
receptacle of the smaller spores. E, large spore magnified. F, group of four 
small spores. G and H, sections of the receptacles. 
ISOETES LACUSTRIS. 
EUROPEAN QUILLWORT. MERLIN’S GRASS. 
Cha. — Leaves awl-shaped, bluntly quadrangular, formed of four 
transversely-jointed longitudinal tubes. 
Syn. — Isoetes lacustris of all modern botanists. 
Fig. — E. B. 1084.— Flo. Lon. N. S. 131 .—Bolt. 41 .—Flo. Dan. 191 .—Schk. 
fit. 173. 
Des. — Root-stock a kind of corni bearing, long, branched, smooth 
radical fibres. Leaves radical, tufted, filiform or awl-shaped, 2 to 4 
inches high, light green, and very brittle. Receptacles immersed in 
the base of the leaves : the outer, which are also the larger and older 
leaves, bearing large spores, the inner and younger leaves producing 
small spores, as explained in the Introduction. 
Mr. W. Wilson finds two varieties in Wales ; the one densely tufted, with slender 
erect leaves, the other with broader and widely-spreading leaves. The former of 
these, Dr. Hooker thinks, may be the Isoetes setacea of Bose. Sprengel says, 
“ that the plant grows at the bottom of carp-ponds, where it would not be of very 
easy access, did not the fish assist the botanist by disengaging it from the mud, 
when it is found floating at the edges of the pond.” 
Sit. — Found only in the extreme north of Wales, north of England, and in 
Scotland, which is a curious circumstance, because submerged water plants are not 
in general so strictly confined to particular latitudes or altitudes. 
Hab. — Scot. : Loch Callader, Aberdeenshire, and Loch Brandy, Forfarshire, 
Mr. W. Brand. Loch Whirral, Forfarshire, Dr. Graham. Loch Tay, Perthshire, 
Dr. Greville. Most of the Scottish Lakes, Mr. II. C. Watson. — Ire. : Lakes in 
the Rosses, Donegal, Rev. Mr. Murphy. — Eng. and Wales : Prestwich Carr, 
Northumberland, B. G. Ulleswater, Cumberland, Mr. Williams. Coniston Lake, 
Miss Beever. In Llyn-y-cwm, Pfynnon Frich (Snowdon), Lake Owgan and 
Llanberris lakes ; also in Floutern Tarn, between Scale Force and Whitehaven, 
Mr. W. Wilson. Lakes of Denbighshire, Mr. J. E. Bowman. 
Geo. — More copious in Sweden and Denmark than elsewhere. New York and 
northwards in America. 
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