118 FLOEA OF WASHINGTON AND VICINITV. 



*Sparganium simplex, Hudson, var. audrocladuia, Gray. 

 July. 



, NA.IADACEiE. 



PoxDWEED Family. 



17aias flexilis. Eostk. Naiad. 



No liowers or fruit yet fotind on this plant. 



Potamogetou uataus L. Poxdweed. 

 Eastern Brauch. Fruit, July. 



Potamogetou daytonii, Tuckerru. 

 Difficult Eun. Fruit. July. 



Potamogeton hybridus, Michx. 



Pouds near tlie t-aual. below Great Falls. Fruit, July. 



Potamogeton loncliites, Tuckerm. 



Flowers iu August : fruit not collected. 



Potamogeton lucens, L. 



Seen iu the Potomac as late as October, but always without spikes and wholly 

 submersed. 



tPotamogeton perfoliatus, L. 

 Potomac. Fruit, July 2, 1876. 



Potamogeton pauciflorus, Pursh. 



P'XjIs among rocks at Little Falls. Fruit, July 13, 1879. 



Potamogeton pectinatus, L. 



Common in the Potomac, but as far as yet observed without tlowers or fruit. 



ALISMACE-aS. 



Watek-Plaxtaix Family 



^ Alisma Flantago, L.. var. Americanum, Gray. Water-Plaxtain. 



Under certain circumstances this plant presents floating leaves with long petioles 

 and elliptical blades like the Potamogetons. July ; floating loaves in April or May. 



tSagittaria variabilis, Eug. Aurow-head. 

 July to September. 



Sagittaiia variabilis, Eng.. Aar. angustifolia, Gray. 



Flats below Eads' Mill. A com])lete series may be collected in which the leaves 

 vary in form from linear to ovate. September. 



f Sagittaria heterophylla. Pursh. 



First found under the Aqueduct in Foundry Run, but this locality is now de- 

 stroyed ; since found on the Carberry Meadows. July to September. 



i^Sagittaria pusilla, Nutt. 



In the Potomac below Analostan Island, on muddy bars between tides. July, 

 August; fruit, last of September. 



