106 
Potamogeton pusillus, ZL. 
Marblehead (Rev. J. L. Russell), Danversport, in brackish water; 
outlets of Wenham and Chebacco ponds. 
Var. tenuissimus, Mertens & Koch. 
Wenham pond. 
Potamogeton gemmiparus, Robbins. Potamogeton pusillus, 
var. (?) gemmiparus. (Gray’s Manual). | 
Wenham pond. 
Potamogeton Robbinsii, Oakes. 
‘¢Wenham pond, 1829” (Oakes in Hovey’s Mag., Vol. VII), the 
original discovery; Crane pond, West Newbury; Sluice pond, and 
abundant in Flax pond (C. E. Faxon). Single specimens have been 
noticed at Pleasant pond, Wenham, and Ipswich river. It varies 
to small forms. 
Potamogeton crispus, L. 
Spy pond, Arlington, 1880 (C. E. Faxon). Probably introduced. 
ALISMACEA. 
(WATER-PLANTAIN FAMILY.) 
Triglochin maritimum, L. 
Salt marshes. Common. 
Scheuchzeria palustris, L. 
‘¢Wenham swamp, 1824” (memo. Dr. Chas. Pickering). 
Alisma Plantago, Z., var. Americanum. 
Wet places along roadsides and railroad beds. Common. 
Echinodorus parvulus, Fngelm. 
Near Cambridge (Prof. James); Winter pond, Winchester (E. H. 
Hitchings). This little plant ought to be found within the limits 
of the county as it occurs so near us. 
Sagittaria variabilis, Engelm. 
A plant of many forms. 
Var. obtusa. 
Georgetown (Mrs. Horner); Essex, etc. Quite common. 
Var. latifolia. j 
Brooks and meadows. Frequent. 
Var. hastata. 
Ditches, etc. This is the most common form. 
Var. diversifolia. 
Pleasant pond, Wenham. 

