Potamogeton.] naiadace^. 535 



In ponds and ditches, probably common. Fl. June, July. 2^. 

 E. Med. — Marsh-ditches at Sandojvn. 



4. P. crispus, L. Curled Pondweed. " Stem compressed, 

 leaves lanceolate waved and serrated 3 - nerved sessile, fruit 

 beaked."— .Br. Fl. p. 468. E. B. t. 1013. 



In ponds, ditches and slow streams. Fl. June, July. If. 

 E.Med. — Marsh-ditches at Sandown. Pond at the brick-kiln, Bembridge, 

 Dr. Bell- Salter. 



W. Med. — Ditches in the marsh at JEaston, abundantly. 



*** Leaves alternate, all linear, submersed. Stipules free. 



5. P. 2>usillus, L. Small Pondweed. " Leaves narrow-linear 

 3 — 5 nerved with obscure connecting-veins, peduncles 2 — 3 times 

 longer than the somewhat lax spike, stem slightly compressed." — 

 Br. Fl. p. 467. E. B. t. 215. Fl. Dan. ix. t. 1451. 



In ditches and stagnant water, both fresh and brackish ; not rare. Fl. July. 



n- 



E. Med. — Marsh-ditches by the Dover at Ryde, abundantly. Brading marshes, 

 in profusion. Marsh-ditches between Brading and St. Helens, Frederick Towns- 

 end, Esq., 1844 .'/.' 



W. Med. — Ditches in the marsh near Easton, Mr. W. D. Snoohe. 



The smallest and slenderest of our species. Whole plant submerged, excepting 

 the small flower-spikes, which appear above the surface in July, distinguishing it 

 from the Zannichellia and Buppia, which commonly grow intermixed with it. 

 Root a few brownish slender fibres. Stem, filiform, round or compressed, more or 

 less branched, from a span (as in my specimens) to 1 or 2 feet in length {Sm.) 

 Leaves alternate, those beneath the flower-stalks opposite, an inch or two in length, 

 scarcely a line in breadth (except in the larger variety, P. compressus of authors), 

 olive-green, acute, with a distinct central rib, and one often obscurely marked on 

 each side near the margin, arid which joins the midrib a short distance from the 

 point of the leaf. Spikes ^rd of an inch long, several times shorter than their 

 stout peduncles, that are often thicker than the stems themselves, of mostly 2 

 interrupted whorls of greenish flowers. Peduncles dilated and compressed below 

 the spikes. Fruit roundish ovate, tipped with the somewhat oblique obtuse 

 stigma. 



**** Leaves alternate, all submersed. Stipules adnate. 



6. P. pectinatus, h. Fennel-leaved Pondweed. " Leaves disti- 

 chous setaceous or linear 1 — 3 nerved sheathing by means of their 

 adnate stipules, spike interrupted, achenes large 3 -ribbed at the 

 back, the two lateral ribs sometimes obsolete." — Br. Fl. p. 466. 

 E. B. t. 323. 



In rivers, ponds and ditches, both of fresh and salt water. Fl. June, July. 

 Fr. July, August. If. 



E. Med. — Ditches on Brading marshes, 1844. Ditches around Sandown fort, 

 1842. 



W. Med. — In a small pool on the marshes at Barnfield, near Yarmouth, 1844. 

 Ditches in the marsh at Easton, plentifully, and appearing to be the large-fruited 

 salt-water variety of the plant, the P. marinum of L. and DC, &c. 



Herb very variable. Root perennial, originating from a tuberous lump, then 

 creeping horizontally, slender, much' branched (Sm.) Stem floating, various in 

 length according to the depth of water, from 1 foot in still to 8 or 10 feet in run- 

 ning water (M. et K.), round, finely striated, copiously branched, the branches 

 repeatedly forked, hence having a fasciculate appearance. Leaves numerous, 



