514 NAIADACEjE 



combined carpels. — Salt marshes ; common. — Ft May — Septem- 

 ber. Perennial. 



2. Scheuchzeria, represented by the one species S. palustris, 

 has a long, creeping rhizome; leaves linear, semicylindric, with 

 swollen brown sheaths ; flowers 4 — 6, in a loose, bracteate raceme, 

 perfect ; perianth of 6 similar, reflexed, green leaves j stamens 6 ; 

 carpels 3, united below. — Peaty bogs ; very rare, found only in 

 the north. (Name from the Swiss naturalists, the Scheuchzers). — 

 Fl. July. Perennial. 



3. Potamogeton (Pond-weed). — Floating or submerged plants, 

 with translucent or opaque, leathery leaves, scattered or opposite, 

 generally stipulate ; flowers in a spike, perfect ; perianth of 4 

 small, green, valvate, persistent leaves ; stamens 4 ; carpels 4, 



potamogeton nAtans {Floating Pond-weed), 



sessile, free, 1 -seeded. (Name from the Greek pdtamos, a river, 

 and geiton, a neighbour.) 



* Leaves scattered, or the upper opposite, oblong, obovate or 

 lanceolate, involute ; stipules free 



1. P. ndtans (Floating Pond-weed). — An aquatic plant, with 

 cord-like stems, proportioned to the depth of the water in which 

 it grows ; upper leaves floating, on long stalks, smooth, leathery, 

 elliptical to lanceolate, 2 — 6 in. long, with small auricles and very 

 long, pointed stipules, lower not always present, submersed, 

 reduced to very narrow linear phyllodes a foot long ; flowers 

 numerous, small, green, in dense cylindric spikes which rise 

 above the surface of the water on stout, axillary peduncles ; carpels 

 rather large, keeled, with a short beak. — Ponds and ditches ; 

 common. — Fl. June — September. Perennial. 



2. P. polygonifolius. — A more membranous plant with long- 



