REVISION OF THE GENUS NAJAS OF LINNJEUS. 275 
by a spiny, acute, brownish-yellow cell. In N. flexilis (fig. 1) this pro- 
minence is formed of the 
spiny cell only, in NW. gra- 
minea (fig. 2) by two, and 
in N. minor and arguta 
(fig. 3) several, additional 
cells. 
Nagas, Linn. 
Sect. I. EUNAJAS.— 
Stem and back of leaves 
generally covered with mi- 
nute spines ; flowers (probably in all species) dioicous. (It remains 
still to be ascertained whether the anthers of all the species of this 
section are different from those of the second.) 
, ; N. marina, Linn. ez parte. A polymorphous and 
widely-distributed « "pcs, the extreme forms of which would hardly 
be recognized as belonging to one and the same species. The normal form 
exhibits the following characters :—Stem sparingly beset with spines 
(10-40 in each internode) ; leaves broad-linear, each edge of the blade 
with 4-8 tecth, which are patent and not quite so long as the leaf is 
broad, the leaf at the back furnished with 1—4 spines ; sheath of leaf with 
rounded lateral edges and without teeth; fruit 5—8 millimetres long.— 
Europe, Northern Asia, Florida (Cabanis!). Under the name of N. ma- 
rina, Linnzus comprehended both N. major and N. minor ; and it does 
not seem advisable, as the Swedish botanists have done, to retain the 
name marina for N. major, especially as that species is a plant found in 
fresh or only slightly-braekish water. Idistinguish the following varieties: 
B. Ehrenbergü, A. Braun. Differs from the normal form by its un- 
armed stem, and the edge of the sheath furnished with 1-2 teeth.— 
Arabia (Ehrenberg !). 
y. angustifolia, A. Braun. Stem almost unarmed; leaves long, 
narrow-linear, on each side of the margin with numerous (5-10) short 
teeth, turned outwards ; sheath generally toothless.— Oahu, Sandwich 
Islands (v. Chamisso !), Boudin (Herb. puru Similar forms also 
found on the coast of Northern German 
8. multidentata, A. Braun. Leaves on ee side of the margin with 
8-11 large and patent teeth, which are longer than the blade is broad ; 
edge of the sheath with 2 or 3 teeth.—Italy (v. Martens !). 
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