5l8 NAIADACEAE 



hxit Mr. Boswell has assured me that he never gathered it in the county, 

 nor is it represented in his herbarium from our district. Probably he may 

 have recorded P. fframinetnii, auct., by which he would mean P. compressum 

 (P. zosterifolhis). The recoid of Bulmarsh Lake in my Flora of Oxfordshire 

 belongs to P. obtvstfolius, which, by a slip of the pen, Mr. Tufnail marked 

 in his Catalogue as this species. P. gramineum should be found in Berkshire, 

 as it is recorded for Surrey, Hants, and Wilts. I very much doubt the 

 Oxfordshire records. Until we have confirnaation of its occurrence in Berk- 

 shire, the species must be bracketed.] 



[P. NiTENs, Web. Fl. Holsat. Supp. No. ii (1787). Syme, E. B. ix, 36, t. 1407. 

 Is found in Surrey.] 



P. lucens, Linn. Sji. PI. 126 (1753). 



Top. Bot. 417. Syme. E. B. ix. 38, t. 1408. Nyman, 682. Fl. Oxf. 282. 



Native. Lacustral. Rivers, canals, ponds, kc. Abundant and generally 



distributed in our larger streams. P. June July. 

 First record. Oxford, Sir J. E. Smith, Herb. Linn. Soc. 1800. S. Hinksey, 



Mr. Baxter, MSS. 1823, 



This is perhaps our commonest species of Pondweed. Very fine 

 specimens are to be seen in the Thames, as at Ferry Hinksey, and in 

 the Kennet and Loddon. It exists in several forms, but the most 

 noticeable one is that in w^hicli the mid-rib is prolonged beyond the 

 leaf lamina ; this is, I believe, the var. acuminatus, Fries, Nov. Fl. 

 Suec. 46 (i8i6)=P. acwninatua, Schum. Enum. PI, Saell. 49 i8oij, 

 "which in some districts is commoner than the form in which the mid- 

 rib is not prolonged beyond the leaf blade. 



P. lucens is found in all the bordering counties. 



[P. DECiPiExs, Nolte ex Koch Syn. ed. 2, 779 (1843-5). Syme, E. B. ix. 39, 

 t. 1409. El. Oxf. 283. Is recorded for Oxfordshire, Surrey, and Hamp- 

 shire.] 



[P. ANorsTiFOLius, Prcsl, Eostlin, i. 531 (1820) = P. Zizii, Koch ex Both Enum. 

 PI. Germ. i. 53t, is recorded for Surrey. 



In the Index Keioensis, P. arifjustifoUus, Bercht. & Presl in Eostlin, i. 

 Alismac. 19, is said to be synonymous with P. pectinatum.] 



P. praelong'us, Wulf, in Roem. Arch. 3, iii. 331 (1803-5"). 

 Top. Bot. 419. Syme, E. B. ix. 41, t. 141 1. Nyman, 682. Fl. Oxf. 283-4. 

 Native. Lacustral. Rivers and canals. Locally common. P. May-June. 

 First recorded by Mr. W. Borrer m E. B. Suppl. t. 2858, 1841 ; see also 

 Plnjt. 28, 1841. 



2. Ock. Abundant in Thames bet\\^een Oxford and Sandford, Dyei: 



Still plentiful in the Thames between the University Boat 

 House and Ififley. Between Iffley and Sandford, see Rep. of Bot. 

 Exch. Clifb, 1892. Near Abingdon. Near Sutton Courtney. Near 

 Dorchester. In the Canal at Uflfington, at Wantage, and 

 between Wantage and Abingdon. 



3. Pang. In the Thames at MouJsford and near Pangbourn. 



