18 
5. POTAMOGETON NUTTALLH, Ch. and Sch. Linnza, ii. 226, t. vi. f. 
25 (1827). 
P. Pennsylvanicus, Ch. and Sch. Linn. ii. 227 (1827). 
P. pumilus, Wolfg. in R. and S. Mant. iii. 354 (1827), fide. Ar. 
Benn. Jour. Bot. xxix. 307. 
P. Claytonu, Tuckerm. Am. Jour. Sci. and Arts, Ist, ser. xlv. 38 
(1843 
Stems slender, compressed, mostly simple, generally from г to 
3 feet high, but sometimes 6 feet according to the depth of the 
water in which it grows. Floating leaves elliptical, sometimes 
obovate, obtuse at the apex, sloping at the base into a short 
petiole, 112-314 inches long and 4-12 lines wide, 12-27 nerved. 
These leaves sometimes number as many as 4 or 5 pairs at several 
inches distance from each other on the upper part of the stem. 
Submerged leaves linear, 2-ranked, 2-7 inches in length and 1-3 
lines in width, 5-nerved, the 2 outer lateral nerves nearly marg- 
inal, the space between the two inner and the midrib evenly and 
coarsely cellular reticulated. In young plants the submerged leaves 
are often crowded close together, the internodes afterwards elon- 
gating. Stipules obtuse, hyaline, nerved, keelless. Peduncles 
about the thickness of the stem, 1-5 inches long. Spikes %-І 
inch long, fruiting freely. Fruit roundish-obovate, 11/—134 lines 
long by 1-114 lines broad, 3-keeled, middle keel sharp, the sides 
flat and distinctly impressed; style short, apical. Embryo coiled 
114 times. | 
Abnormal forms occur with stems bearing many short lateral 
branches, and with branched peduncles. 
As has been stated under No. 2, I regard this species as con- 
forming so closely to the figures and description of the fruit of P. 
Nuttallit, as given by Cham. and Sch., that I cannot question their 
identity. Otherwise I should have adopted their name P. Pennsyl- 
vanicus, given a little later in Linnza, of which only the foliage is 
described. The truth seems to be that only fruit was seen in the 
one case and only foliage in the other, and these authors described 
them under different names. 
So far as known, this species is peculiar to this country. 
Common in ponds and streams throughout Canada, and from 
New England to Pennsylvania and South Carolina, and westward 
+ 
