POTAMOGETON ZIZII AS A BRITISH PLANT. 291 



accord it a similar rank. Curiously enough, the plant is not men- 

 tioned at all in Nyman's ' Sylloge.' 



If the German authors for the most part are thus inclined to 

 place this pond-weed with P. heteroplujUus (unless they kee^) it as 

 a species), on the other hand the Scandinavian botanists with 

 greater propriety jDlace it under P. litcens. Thus Nolte'" calls it 

 P. lucens var. minor, Fries! P. lucens var. heterophyllus, and Hart- 

 man I and A. Blytt § P. lucens var. Zizii. Ascherson also, in his 

 excellent Flora, is in accord with these, and places it as a 

 Viiriety of P. lucens. \\ Probably the arrangement most in accord- 

 ance with nature, however, is that followed by Chamisso and 

 Schlechtendal in their monograph of the genus published in 1827,^ 

 where P. Zizii is accorded equal rank with P. lucens and P. hete- 

 lophyllus, all being regarded as sub-species of one super-species, 

 P. Froteus, C. & S. 



These various synonyms and some others are shown in the 

 following list : — 



P. Zizii, Mert. d- Koch (Both, Fieber, Lange, Keichenbach). 



P. angustifolius, I'resl (fide Fieber). "'•= 



P. lanceolatus, Wolfffaur/ (nou Smith nee Keichenbach). 



P. gramineus var. platyphyllus, Meyer. 

 ,, var. Zizii, Koch (Kuuth). 



? ,, var. s^Dathaeformis, Tuckerman. 



P. heterophyllus, var. latifolius, Mert. d Koch. 

 ,, var. Zizii, Boreau. 



P. lucens var. minor, Nolte. 



,, var. heterophyllus, Fries. 

 ,, var. Zizii, Ascherson, Blytt. 

 ? ,, var. coriaceus, Xolte. 



P. Proteus, sub-sp. Zizii, Cham, d Schlecht. 



P. serratus, Linn. Sp. PL, Nolte in Hansen, Herb. Slesv.-Holst. 

 n. 1114 (Herb. Mus. Brit.) 



Figures. — P. Zizii is well figured in Eeichenbach's ' Icones 

 Fl. Germ.' vii. t. 39 (var. eloiujatus) and t. 38 (var. validus) ; but 

 Koch considers the latter to represent at all events partly P. lucens. 

 The fruit is also figured in the 'Linnaea,' ii. (1827), t. v. fig. 16 h,c, 

 and in Fieber, 'Die Potamog. Bohmens ' (1838), t. ii. fig. 11. 

 I hesitate to quote the large new plate of P. Zizii in ' Flora 

 Danica,' fasc. 49 (1877), t. 2886, which differs in several parti- 

 culars, especially in the form of the perianth-leaves. 



Distribution. — The plant has been observed in many parts of 

 the north and centre of Europe. In the herbarium of the British 

 Museum we have examples from the Palatinate (where it was first 

 noticed), and from Eiiangen, Bavaria ; from Slesvig-Holstein, 

 Saxony, Silesia, Bohemia, and the island of Bornholm in the 



* In Hansen. Herb. Slesv.-Holst., no. 021 (Herb. Mus. Brit.) 

 + Fries, ' Novitise Fl. Suec.,' p. 3t). 

 + Hartm., ' Skandin. Fl.' ed. 10, p. 2-2G. 

 § Blyth, ' Norges Flora,' Suppl., p. 1277. 

 II Asch., ' Fl. Prov. Brandenburg,' p. 050 (1864). 

 II In ' Linnaea,' ii. p. 201. 

 ** This is not improbably an earlier name, but I have been unable to trace it. 



