POND-WEED FAMILY 5I5 



Stalked leaves, the upper opposite, obovate to lanceolate, rounded 

 at the base, lower linear-lanceolate ; flowers in slender spikes on 

 slender stalks ; carpels very small, not keeled, red, with very short 

 beak. — Ponds; \ery common. — Fl. June — September. Peren- 

 nial. 



3. P. fli'iitans, — A rnre form with an unbranched stem; very 

 long, submerged leaves and rather leathery, floating ones, and a 

 fruit resembling that of -P. ndians. 



4. P. colordtus (Plantain-leaved Pond-weed). — Leaves mostly 

 submerged, long-stalked, membranous, pellucid, beautifully 

 netted, broader than those of the preceding species, elliptic- 

 orbicular, on slender stalks, with short, broad, blunt stipules ; very 

 slender peduncles; carpels very small, rounded, green. — Peaty 

 ditches ; uncommon. — Fl. June — September. Perennial. 



5. p. alpinus (Reddish Pond-weed). — Stent round, unbranched, 

 I — 4 feet long ; leaves reddish, lanceolate, translucent, upper 

 short-stalked, broader, floating, or erect, rather leather)- ; lower 

 submerged, sessile, many-nerved ; stipules large, blunt ; flowers in 

 stout spikes on stout stalks ; carpels ovoid, pointed, keeled, red. — 

 Ditches ; frequent. — F'l. July— September. Perennial. 



6. P. sparganiif alius (Bur-reed-leaved Pond-weed), known only 

 in Gahvay, has a slender, slightly-branched stem ; long leaves, the 

 upper often absent, or long-stalked, floating, and rather leathery, 

 the lower linear and many-nerved ; and long stipides. 



7. P. lanceoldtus (Lanceolate Pond-weed). — A very rare species 

 with very slender, fragile stem ; dark green, oblong, obtuse, 

 pellucid, reticulate leaves, with slender, pointed stipules ; flowers 

 in short spikes on short, slender stalks, and carpels 3-toothed. — 

 Rivers in Cambridge, Anglesea, and Down. — Fl'. July — September. 

 Perennial. 



8. P. heterophvllus (Various-lea\ed Pond-weed). — Stem slender, 

 round, 2 — 4 feet long, much branched below ; leaves flat, upper 

 floating, opposite, leathery, elliptic, lower subfnerged, lanceolate, 

 flaccid ; stipides small ; flowers numerous in* dense spikes on 

 stout, axillary and terminal stalks which thicken upward ; carpels 

 small, 3-keeled, with a short beak. — Ditches; frequent. — Fl. |une 

 — September. Perennial. 



9. P. fahdtus. — A dark green or reddish-green plant, with a 

 tuberous rhizome; slender, round stem, branched below; leaves 

 amplexicaul, entire, flat, upper leathery, with 6 opaque ribs on 

 each side of the mid-rib, lower with 3 ; Stipules herbaceous, 

 persistent ; flowers in a dense, cylindric spike about an inch long 

 on a slightly longer peduncle ; fruits small, dark green, rounded, 

 keeled, with a prominent beak. — Xear Ramsey, Huntingdon. 



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