Is^OTES ON BRITISH POMATOGETOXS 15 



seed, though no doubt this is rare — I have only seen good fruit on 

 deep-water forms from Derwentwater, Cumberland (Fearsall), and 

 from Butterstone Loch, Perth {Sturi^ocJc). We do not seem to have 

 any form like f . spJendissima Tis., with peduncles 28 cm. long ; the 

 nearest to it is from Cauldshields Loch, Roxburgh (^BrotJierstoii), 

 with peduncles 20 cm. long. Of the Cambridge Fens forms, a large 

 number fall imder var. vciUcIks Tieb., f. coriaceus M. et K. (P. 

 coriaceus Fr^^er) ; our usual form is lucescens Tis. : f. communis 

 Hagst. occurs in Llyn Leydyard ( Griffitlis) ; f. lucentijormis Hagst., 

 Westmoor, Cambs {Fryer) ; var. elongatiis f. foJiosiis occurs in 

 Coniston Lake, N. Lane. (C Bailey). The most remarkable state 

 is one from Great Fen Acre Drain, Chatteris, Cambs {'Fryer) with 

 petioled upper leaves 20 cm. long X 40 mm. wide. 



*P. ^iJjIjIjVBTL YYjQY=angustifoliusX colorattis, P. coloraUisX 

 gramineus Hagst. (p. 181), P. coriaceus X2^l(int<:tgine us Fryer. 

 "The English specimens I have examined are by Fryer himself 

 determined as P. BiUiipsii, and considered to be a combination of 

 his P. coriaceus Sind coloratus, which would mean P. gramineus X 

 lucensxcoloratus , anything of P. lucens, however, cannot be dis- 

 covered in the specimens here concerned, .... in the specimens 

 figured [as Billvpsii'] in t. 337 [Journ. Bot. 1893] are evidently 

 P. Zizii .... in the specimens figured on Plate 338 P. coloratus can 

 easily be traced in the leaf -texture " etc. 



The only other habitat given by Hagstrom for this hybrid is 

 Gothland, Sweden : I know too little of the plant to venture an 

 opinion concerning it. 



*P. VAEiANs Morong ex Fryer (p. 205). Hagstrom puts this 

 under gramineus L. He considers the Fryer specimens nos. 1732, 

 2243, & 1277 Gunty Fen are " pure nigrescens Fries ; likewise also 

 no. 2056, 2057 from Block Fen, and 2504 from Witcham Headlands, 

 Mepal." Here I am disposed to agree, but much difference of 

 opinion has been, and will continue to be, expressed as to Fries's 

 plant. 



*P. CEASSiroLius Fryer = P. gramineus x lucens x natans 

 (p. 216). "The specimens from Cambridgeshire, Westmoor, 

 Doddington (P. crassifolius f. verrutus Fryer) under no. 1668, . . . 

 also nos. 422 and 423 from Doddington, seem to be this double 

 hybrid." Other " Fryer specimens of P. crassifolius " Hagstrom 

 (p. 239) places under P. lucens X natans : 1 think he is probably 

 nght here, as I knoAV some of the early gathered plants referred to 

 crassifolius were a state oifiuitans Both. { — lucens X natans). 



P. Geiffithii Ar. Benn. (p. 149). Hagstrom identifies this with 

 P. nerviger Wolfg. from Lithuania : this and the Welsh station are 

 the only ones known. "Its hybrid origin (i.e. P. alfinusxyrcB- 

 longus) is beyond all doubt and may nowadays be disputed in earnest 

 by nobody " ; nevei-theless, I venture to do so. To begin with, the 

 habitats are very different — Lithuania a low-lying marshy country, 

 Lljm-an-afon (Aber Lake) an isolated mountain tarn with wild 

 scenery around. Moreover, P. prcelongus is not known in Caernar- 

 vonshire ; P. alpinus grows only in one spot, thirty miles away. 



