APOCARPE.E 379 



This species is found in all parts of the British 

 Isles, as far north as the Shetland Isles, and in 

 Ireland and the Channel Islands. 



Lakes, ponds, stagnant or running water, deep or 

 shallow ditches, etc., are the habitats of this species. 

 It grows in the fresh-water aquatic formation in 

 waters relatively rich in mineral salts, in nearly 

 stagnant waters, in the floating-leaf association, and 

 in waters poor in mineral salts, in peaty moorland 

 lochs, and in the open reed-swamp. 



The plant has the aquatic habit. The rhizome is 

 sympodial, creeping. The stem is round in section 

 and simple. The branches are erect and leafy. They 

 die down in winter, only the rhizome persisting. 

 The leaves are long-stalked, the upper leaves floating. 

 There are no submerged leaves, or if so they are 

 phyllodes. The floating leaves are elliptic to lance- 

 shaped, ovate, oblong, leathery, thick, opaque, 

 rounded below or heart-shaped, or tapering, with 

 several longitudinal nerves, alternate, the blade 

 running down the leaf-stalk. The margins are 

 incurved, folded below. The leaf-stalk is jointed just 

 below the limb, plane to concave. If flattened a 

 ridge is formed on each side of the base. The sub- 

 merged leaves are thin, narrow, stalked, linear to 

 lance-shaped, bristle-like, or mere leaf-stalks. The 

 stipules are free, very long, axillary, closely sheathing, 

 long-pointed. 



The flowers are in a dense, cylindrical spike, pro- 

 jecting above water, an inch or more long, on a stout 



