PQTAMOGETON UNDULATUS IN SCOTLAND 105 



I am now able to report the true plant from Scotland, 

 whence it was sent me by Mr. Kidston, whose label is as 

 below : 



" Potamogeton prczlongns, Wulf. Kildean. River Forth 

 near Stirling. Sept. 10, 1894. Stirlingshire." 



The false report of the plant before, naturally made one 

 very cautious as to a second one, and it was not till recently 

 that, on a careful comparison of Mr. Kidston's specimens with 

 types gathered by Wolfgang and Besser in Lithuania, and 

 Caspary in Prussia, which I possess, they were found to be 

 identical. The Scotch specimens are absolutely sterile (in 

 my specimens), the flowers that remain unopened, though 

 most had fallen off; if anything they are rather more 

 towards prcelongus, while Caspary's are more towards crispus, 

 Wolfgang's original specimens being exactly intermediate. 

 It differs from prcelongus by being sterile, the apex of the 

 leaves scarcely cucullate, and by the stem being compressed ; 

 from crispus by the non-serrated edge of the leaves, the 

 greater number of nerves, with more numerous cross veins ; 

 from perfoliatus by possessing numerous bast-bundles in the 

 bark, and by differences in the axial cylinders. I give the 

 original description, etc. 



POTAMOGETON UNDULATUS, Wolfg. (Besser in lift.}, in 



Roem. and SchuL, " Sys. Veg. Mant." iii. 361 (1827). 

 P. CRISPUS, / Eiclnvald, " Nat. Skizz.-Lithauen," etc., 



105 (1830). 



P. CRISPUS, var., LEDEBOUR, " Fl. Ross." iv. 29 (1853). 

 P. CRISPA x PR.ELONGUS, Caspary in " P. Oe. G. 



Konigl." v. i 8, 99 (1877). 

 P. DECIPIENS, Nolte, teste ScJnnaUiausen, ex. Nyman. 



" Consp. Fl. Europ." supp. 287 (1890). 

 P. CRISPUS, L., Richter, " Fl. Europ." i. 14 (1890). 

 P. PR/ELONGUS x CRISPUS, Asch. and Gracb. " Syn. Fl. 



Mitt.europ." i. 338 (1897). 

 RAUNKL-ER, Danske, Blomsterpl. 105 (1895). 



" Caule compresso, sulco utrinque longitudinali fluctanti, 

 inferne ramosa ; foliis omnibus submersis, membranaceis, 

 integerrimis, alternis, oblongo-ovalis, lanceolatis, rotundato- 



