﻿labelled "Perth, Laird's Loch, Aug., 1873. A. Sturrock." This 

 specimen I had named " var. pseudo-fiuitans ?," and now I have 

 examined the Edinburgh types, I have no doubt about the correct- 

 ness of the reference. Also a specimen labelled " Potamogeton , 



Tiggan, Orkney Isles, 1875, leg. J. B. Syme," belongs to the same 

 variety. 



I am induced by the examination of a great number of speci- 

 mens of P. polygonifolim to think that species, like P. natans, has 

 no permanent true varieties, but that the forms are mere states due 

 to local surroundings, and which, under altered conditions of 

 growth, would lose their distinctive features and revert to the 

 ordinary heath or shallow-water form, which I take to be the type 

 of the species. It is to be hoped that the polygonifolim form of the 

 Eiver Leven will be examined by some botanist who may have the 

 opportunity of observing them at different seasons of the year, and 

 of comparing the deep- and shallow-water forms while actually 

 growing. If this be done, and if roots of the different forms be 

 properly cultivated, we shall then have firmer grounds on which to 

 base an opinion than any quantity of dried specimens can afford. 



In the case of P. natans there is no form of leaf, and no 

 peculiarity of habit, which cannot be produced from one rootstock 

 by skilful cultivation ! And as far as my limited experience in 

 growing P. polygonifolim goes, I am inclined to think that similar 

 results may be obtained by cultivating it under varying conditions. 

 I would suggest to any botanist who may wish to test the deep- 

 water forms by growing them, that the first aim should be, after the 

 rootstock is fairly established in deep stagnant water, to obtain the 

 land-form. This can be done by gradually diminishing the depth 

 of the water until the whole of the foliage is completely exposed to 

 the air. Then let the rootstock be transferred to a shallow stream, 

 which should be gradually deepened as growth proceeds. 



In regard to the specimens described in the present note, I 

 think they grew in deep running water which became shallow, but 

 not much less swift, as the plant came into flower. Looking at the 

 Gamlingay specimens, I cannot regard var. pseudo-fiuitans as a 

 rather as a state of the 

 any locality by suitable 



Before concluding this note, it will be as well to explain the way 

 in which Mr. Morgan has produced his beautiful and faithful plate, 

 the very best I have yet seen of any Potamogeton, As the speci- 

 mens lie on the sheets to which they are fastened, little of the 

 venation of the leaves is to be seen, and to draw or to examine 

 just the surface of a Potamogeton that one does see in this condition 

 of a dried specimen is of little use ; so the plant is held up to the 

 light and the net-work of veins is represented as thus seen. No 

 restoration of damaged leaves and no " improvement " of Nature 

 has been attempted. Unfortunately the size of the plate has com- 

 pelled a reduction of one-third less than the natural size, but in all 

 other respects the plate may be studied with almost as much 

 advantage as the original s 



