PONDWEED FAMILY. 67 
3. Potamogeton amplifdlius Tuckerm. Large-leaved Pondweed. (Fig. 144.) 
Potamogeton amplifolius Tuckerm, Am. Journ. Sci. 
(II.) 6: 225. 1848. 
Stems long, simple or occasionally branched. 
Floating leaves oval or ovate, abruptly pointed at 
the apex, rounded at the base, 2/-4’ long, 14 /—2’ 
wide, many-nerved; petioles 3/-5’ long; sub- 
merged leaves mostly petioled, large, the upper- 
most often elliptic or oval, 3/-6’ long, 1/-214/ 
wide, the lowest lanceolate, often 8’ long, with 
about 25 nerves, often with the sides of the blade 
closed and assuming a falcate shape; stipules 
tapering to a long sharp point, sometimes 4’ 
long ; peduncles thickened upward, 2/-5’ long ; 
spikes cylindric, 1/-2’ long; fruit 2’’-212’’ long, 
1{/’ thick, turgid, the pericarp hard, obliquely 
obovoid, 3-keeled; face more or less angled ; 
style subapical ; embryo slightly incurved. 
In lakes, Ontario to British Columbia, south to 
Connecticut, Kentucky and Nebraska. July—Sept. \ 
4. Potamogeton pulcher Tuckerm. Spotted Pondweed. (Fig. 145.) 
Potamogeton pulcher Tuckerm. Am. Journ. Sci. 
45:38. 1843. 
Stems simple, terete, black-spotted, 1°-2° 
long. Floating leaves usually massed at the 
top on short lateral branches, alternate, ovate 
or round-ovate, subcordate, 2/-414’ long, 9//— 
3%’ wide, many-nerved; peduncles about as 
thick as the stem, 2/-4’ long, spotted; sub- 
merged leaves of 2 kinds, the uppermost pellu- 
cid, lanceolate, long-acuminate, undulate, 3/—S’ 
long, 6’/-18’” wide, tapering at the base into a 
short petiole, 10o-20-nerved ; the lowest much 
thicker, opaque, spatulate, oblong or ovate, on 
petioles %/-4/ long; stipules obtuse or acumi- 
nate, 2-carinate; fruit 2//-21/’’ long, 1%4’’ thick, 
turgid, tapering into a stout apical style, the 
back sharply 3-keeled; face angled near the 
middle, with a sinus below ; embryo coiled. 
In ponds and pools, Maine to Georgia and Mis- 
sourl. July. 
5. Potamogeton Nuttallii Cham. & Sch. WNuttall’s Pondweed. (Fig. 146.) 
Potamogeton Nuttallii Cham. & Sch. Linnaea, 2: 
226. pl. 6. f. 25. 1827. 
Potamogeton Claytonti Tuckerm, Am. Journ. 
Sci. 45: 38. 1843. 
Stems slender, compressed, mostly simple, 
1°-6° long. Floating leaves opposite, elliptic, 
sometimes obovate, obtuse at the apex, short- 
petioled, 114/-34’ long, 4’/-12’’ wide, many- 
nerved; submerged leaves linear, 2-ranked, 2/—7’- 
long, 1’/’-3’’ wide, 5-nerved, the 2 outer nerves 
nearly marginal, the space between the 2 inner 
and the midrib coarsely reticulated; stipules 
obtuse, hyaline, not keeled; peduncles 1/-5/ 
long; spikes 1%4’-1/ long; fruit round-obovoid 
1¢//-2’/ long, 1’/-1%4’’ thick, 3-keeled, the sides 
flat and indistinctly impressed; style short, 
apical; embryo coiled one and one-third times. 
In ponds and streams, Nova Scotia to Pennsyl- 
vania and South Carolina. June-Aug. 
