34 
Leaves of this variety lanceolate, from 1 to 414 inches long and 
4-8 lines wide at the broadened amplexicaul base, often curving 
inwards towards the apex, and from 13 to 23-nerved. Leaves 
from North Hero, Lake Champlain (Morong), and Sault Ste. 
Marie, St. Mary's River, Mich. (Hill), measuring 4% inches in 
length, are the longest that I have ever seen. The fruit is some- 
what larger than in the type, measuring about 134 lines long by 
114 lines wide. 
Forms found in Wenham Pond, Mass., greatly resemble Р. 
nitens, Webber, of Europe, and are considered to be this species 
by Dr. Tiselius. They also bear a strong resemblance to Р. per- 
foliatus, var. Jacksoni, Nees, of England, which is regarded as a 
form of mitens by Prof. Babington. They have oblong leaves 1— 
174 inches long and 4-9 lines wide, obtuse, 7—1 3-nerved, not ser- 
rulate, semi-amplexicaul, with very slender, laterally much-branched 
stems. | 
Common in Canada from Nova Scotia to Ontario (Macoun). 
In the United States it occurs in nearly all parts of the country 
from Maine to Florida, and west to the Pacific. The variety 
occurs in Ontario, Canada, and thence westward, and from Lake 
Champlain, Eastern New York and Delaware westward to Oregon 
and California, being the most common Western form. In still, 
° shallow or deep water. July-September. (Plate XL. Var. Rich- 
ardsonit is figured on the right). 
17. Ротлмосетох Mysticus, Morong, Bot. Gaz. 5, 50 (1880). 
Whole plant very slender and delicate. Stems from a creep- 
ing rootstock which throws up many shoots, irregularly branching 
above, nearly filiform, terete, 1-3 feet high. Leaves all submerged, 
scattered, oblong-linear, 1-114 inches long and 1-3 lines wide, 
5—7-nerved, obtuse and rarely with minute serrulations near the 
apex, abruptly narrowing at the base and sessile or partly clasping. 
Stipules obtuse, about 6 lines long, hyaline, with many fine nerves, 
mostly deciduous, but sometimes persistent and closely sheathing 
the stem. Spikes few, capitate, 4-6-flowered, on erect peduncles 
from I to 2 inches in length. No пре fruit has ever been found, 
but one or two immature drupes indicate that it is obovate, min- 
ute, scarcely 3% of a line long by % a line broad, obscurely 3- 
keeled on the back, a little beaked by the slender recurved style. 
