FLORA OF WORCESTER COUNTY. 55 



AcoRUS, L. Sweet Flag. 



Calamus, L. Moist grounds, not rare. 



LEMNACE^. 



Lemna, L. Duckweed. 



minor, L. Stagnant waters, common. 



ALISMACE^. 



Alisma, L. Water-Plantain. 



Plantago, L. Shallow water, common. 



Sagittaria, L. Arrow-head. 



variabilis, Engelm. In water or wet places. Common. 

 " " var. *obtusa. G. E. Stone. 



" " " *angustifolia. " " 



" " " *diversifolia. Princeton. 



W. W. B. &^J. F. C. 

 " " " gracilis, Engelm. G. E. Stone. 



graminea, Michx. 



NAIADACE^. 



Potamogeton, Tourn. Pondweed. (By the late Rev. Thos. 

 Morong.) 

 natans, L. Very common. 



" " var. *prolixus, Koch. " " 



Oakesianus, Robbins. Uxbridge. 



Pennsylvanicus, Cham. Common in streams and ponds. 

 Vaseyi, Robbins. Lake Quinsigamond. 



Spirillus, Tuckerm. Common. 



hybridus, Michx. 

 fluitans. Roth. Worcester. Miss E. W. Sargent. 



