POTAMOGETON 521 



[P. ACUTiFOLius, Link in Eoem, et Schultes Syst. iii. 513 (i8i8). 



Top. Bot. 415. Syme, E. B. ix. 46, t. 1416. Is recorded for Surrey, and is 



a plant which will probably be found in Berkshire in the southern 



reaches of the Thames.] 



P. obtusifolius, Mert. et Koch, Deutsch. Fl. i. 855. 



P. gramineus, Sm. E. B. t. 2253, not of Linn. Herb. 

 Top. Bot. 415 .Oxford). Syme, E. B. ix. 47, t. 1417- Nyman, 683. 



Fl. Oxf. 285. 

 Native. Lacustral. Lakes. Very local. P. July. 

 First record. Bulmarsh, 'P. heterophyllus,' Mr. F. Tufnail, in Fl. of 

 Oxfordshire, 1886. 

 5. Loddon. Bulmarsh, Tufnail. Eather common in some portions 



of Virginia Water both in Surrey and Berks, 1893. 

 I have not seen the Bulmarsh plant as the owner of the property 

 refused me permission to go over his estate. 



P. obtusifoliiis is recorded for Surrey and Hampshire. 



P. Priesii, Euprecht, Beitr. Pfl. Euss. iv. 43 (1845). 



P. mucronatus , auct. P. grarnineimi, Sibth. Fl. Oxon. not of Linn. 



P. comxyressum, E. B. t. 418, not of Linn. 

 Top. Bot. 414. Syme, E. B. ix. 48, t. 1418. Nyman, 683. Fl. Oxf. 285. 

 Native. Lacustral. Ponds, canals, shallow streams. Locally common. 



P. July. 

 First record. The author in Fl. Oxf. 285, 1886. 



1. Isis. Near Shrivenham. Near Wytham. Near Eynsham. 



2. Ock. Marcham, Fl. Oxf Common in the Canal between Abing- 



don and Wantage. Uffington. Ferry Hinksey. Near Iffley. 



3. Pang. Moulsford. Pangbourn. 



4. Kennet. In the Kennet Canal. Hampstead Marshall, and in 



the Kennet. Near Aldermaston. 



5. Loddon. White Knights' Lake, Tufnail. 



The 1\ compressum of Milne and Gordon may possibly refer to this. 

 P. Friesli is recorded for all the bordering counties. 



P. pusillum, Linn. Sp. PL 127 (,1753). Small Grass-leaved Ponchoeed. 



Top. Bot. 414. Syme, E. B. ix. 49, t. 1419. Nyman, 683. Fl. Oxf. 286. 

 Native. Lacustral. Elvers, ditches, ponds, &c. Fond of slow-running 



or stagnant water. Not uncommon. P. June-July. 

 First record. Potamogeiton Pusillum folio gramineum, caule rotimdo, in 



Thames, near Oxford, MerreWs Pinax, 97, 1666. 



1. Isis. Near Shrivenham. Near Lechlade. Wytham. 



2. Ock. Thames near Oxford, Merrett. Below Iflfley Mill. Frilford. 



Wantage. Marcham. In the Canal between Abingdon and 

 Wantage. 



