78 TTie Flora of Wiltshire. 



1. P. natans, (Linn.) swimming or broad-leaved Potamogeton. 

 Engl. Bot. t. 18^2. Reich Icones. vii., 50. 



Locality. Kennet and Avon Canal, ponds, and still waters. P. 

 Fl. June, July. Area, * * S, 4, 5. Generally distrihUed in all the 

 Districts except 1 and 2. Floating leaves very variable in size and 

 shape, more or less elongated, sometimes linear lanceolate, obtuse at 

 the base, and decurrent with the foot-stalk, with about 7 principal 

 nerves and several intermediate ones, connected with minute reticu- 

 lations, opposite under the flower stalk, involute in bud. Stipules 

 very large, 2 to 3 inches long, lanceolate, acute, concave, pale and 

 membranous. Peduncles suddenly contracted below the spike. 

 Flowers olive-green. The submerged leaves are frequently wholly 

 wanting, especially when the plant grows in very shallow water. 



2. P. rufescens, (Schrad.) reddish Potamogeton. Engl. Bot. t. 

 1286. Reich Icones, vii., 32. V.fluitans, Sm. 



Locality. Kennet and Avon Canal, ditches, slow streams and 

 ponds, not common in the county. P. Fl. July. Area, * * 3, 4, 5. 

 This, in some situations, much resembles the next species, P. lucens. 

 Coriaceous floating leaves nearly as acute as the lower ones, differing 

 only in their firmer texture and in being stalked. Flower-stalk not 

 thickened upwards. The plant is remarkable for its reddish olive 

 colour, and is perhaps better known by its general aspect, size, and 

 hue, than by any character that can be applied to it. 



3. P. lucens, (Linn.) shining Pond-weed. Engl. Bot. t. 376. 

 Beich Icones, vii., 36. 



Locality. In the Upper and Lower Avon, Kennet and Avon 

 Canal, and in deepish water. P. Fl. June. Area, 1, * 3, 4, 5. 

 Observed in all the Districts except the South-middle. The largest of 

 our species and very beautiful in the reticulation of its leaves. Stem 

 thickened upwards, slightly branched. Leaves distantly inserted, 

 alternate, those subtending the peduncles opposite, all tapering at 

 the base, into the foot-stalks, which in the stem leaves are very short, 

 in the upper ones rather longer. Coriaceous leaves, according to 

 Hooker, rare, ovate, lanceolate,- moderately acute. Stipules large, 

 plicate, half the length of the leaves. Spikes 2 inches long. 

 Flowers green. P. decipiens (Nolte) probably only a variety of the 



