Potamogeton.} NAIADACE^. 375 



The hybrid P. rufesoens x heterophyllus is doubtfully recorded 

 as occTirriiig iu Lough. Neagh at Maghery, Armagh : Praeger i8g^. 



5. P. lanceolatus Smith — Lanceolate-lemied Pond-weed. 



Disti-icts — — ___ VI. — — — — — — 



Lat. 53°-53J°. Clare and Galway only. 



Lowland. Streams ; very rare. Fl. July- August. 



VI. In Cahira river south of Black Head; Clare (P. B. 0' Kelly) : 

 -Journ. of Pot. z8qz, p. 344. : — growing here in a rather strong 

 current on a gravelly bottom : Journ. of Bot. iSgs, p. ig$. 



A peculiar form was gathered by Mr. R. LI. Praeger in the 

 Clonbrock river, East Galway in 1896. While placing this in a 

 wide sense under P. lanceolatus, Mr. Arthur Bennett suggests that 

 it should be ranked as a variety or form with the name Mbernious : 

 Ir. Nat. i8g6, p. si^. 



The localities recorded in the first edition of this work are no 

 •doubt errors, so that the title of this rare plant, in its typical form, 

 to a place in the Irish flora rests, so far, on Mr. O'Kelly's interest- 

 ing discovery. 



It has been suggested that this Pondweed, which is apparently 

 -endemic in the British Isles, is of hybrid origin, i.e. P. hetero- 

 phyllus X pusillus, and this should be borne in mind when searching 

 for the plant. 



6. P. heterophyllus Schreb. — Varwus-leaved Pond-weed. 



P. gramineus Fries. 



Districts I. II. III. IV. V. — VII. VIII. IX. X. XL XII. 



Lat. 52°-55J°. Throughout Ireland, probably. Type, British- 

 English. 



Lowland. Ponds, ditches, and rivers ; not infrequent. Fl. 

 June- July. 



Var. GEAMnrrFoinrs Fries — I. River Laune, Kerry, for nearly 

 its whole course : R. W. S. zSgo (as P. nitens var. salieifoUus 

 Pries). — II. In the Blackwater near Eermoy, and in its tributaries, 

 the Puncheon and Owbeg, 1896 ; P. W. S.^V. In the Boyne below 

 Navan, Co. Meath {P. W. 8.) : B. Ex. C. Report i8g3.—t\is. is 

 the plant doubtfully referred to P. heterophyllus in Cyh. zst Ed., 

 -and to P. Lonohites (Tuck.) in Rec. Add. In River Liffey near 

 Lucan and Leixlip, Dublin 1894-95 ; N. C— VI. and IX. In 

 the River Suck at Mount Talbot, Roscommon ; Levinge. 



