183 
Potamogeton oakesianus Robbins, in Gray, Man. ed. 5, 485 (1867). 
This was collected by Herbert J. Webber in 1889, near Thedford, but was not 
obtained by the present collector. 
Potamogeton lonchites Tuckerm. Amer. Journ. Sci. n. ser. vi, 226 (1848). 
Near to the typical form, but with smaller leaves. Norway, June 23 (No. 1421). 
Another form is also referred here, differing somewhat in the shape of the leaves. 
The floating ones are narrow and thin, and only 9- to 13-nerved. Dismal River, June 
26 (No. 1846). 
Potamogeton amplifolius Tuckerm. Amer. Journ. Sci. n. ser, vi, 225 (1848). 
Common: Dismal River, June 26; Swan Lake, August 7; northwest of Whitman, 
September 19 (No. 1440). 
Potamogeton perfoliatus L. Sp. Pl. i, 126 (1753). 
This plant approaches the variety richardsonit A. Bennett, Journ, Bot. xxvii, 25 
(1889). 
In a lake northwest of Whitman, September 20 (No. 1792). 
Potamogeton pusillus L. Sp. Pl. i, 127 (1753). 
In a pool, near Middle Loup River, Thedford, June 21 (No, 1396). 
Potamogeton pectinatus L. Sp. Pl. i, 127 (1753). 
East Cody’s Lake, August 9; lake northwest of Whitman, September 19 (No, 
669). The specimens from the latter locality are of the form that has been called 
variety scoparium Wallr. 
Potamogeton interruptus Kitaibel, in Schultes, (st. Fl. ed. 2, 328 (1814). 
This identification is somewhat doubtful. I have no mature fruit, but the long, 
broad leaves with strong transverse veins point to this species rather than to P. pec- 
tinatus, to one of which it must belong (No. 1489). 
Zannichellia palustris L. Sp. Pl. ii, 969 (1753). 
A small form, less than a decimeter high, rooting in the sand: East Cody’s Lake, 
August 9, 10 (No. 1661). 
Naias flexilis (Willd.) Rostk. & Schmidt, Fl. Sed. 384 (1824); Caulinia flexilis 
Willd. Abh. Akad. Berl. 95 (1803). 
Only a few specimens collected, East Cody’s Lake, August 9 (No. 1660), A more 
slender form, in appearance resembling more the next, but with broader, ovate fruit, 
not pitted, was found at the other end of the same lake, August 11 (No. 1828). 
Naias guadalupensis (Spreng.) Morong, Mem. Torr, Club, iii, 60 (1893); Caulinia 
guadalupensis Spreng. Syst. i, 20 (1825). 
In a lake, northwest of Whitman, September 19 (No.1786). A rare plant in this 
latitude. It was first collected in Nebraska by Prof. Thomas A. Williams, 
CYPERACES.. 
Cyperus schweinitzii Torr. Ann. Lye. N. Y. iii, 276 (1836). 
A very common plant in the sand hills: Thedford, June 20; Norway, June 23; 
Plummer Ford, July 8; Mullen, July 19; northeast of Whitman, July 31 (No. 1371). 
Cyperus houghtonii Torr. Ann. Lyc. N. Y. ill, 277 (1836). 
A rare plant that for some time has been lost to science. It has been held not dis- 
tinct from the preceding, but it can easily be distinguished by the less sharp angles 
of the culm, which are not scabrous, and by its not cuspidate glumes. My speci- 
mens agree fully with Torrey’s description, except that the leaves are a little rough 
on the margin. Old field, near Natick, September 11 (No. 1747). 
Cyperus strigosus L. Sp. Pl. i, 47 (1753), 
A common plant on moist, sandy soil: Cody’s Lakes, August 9; Thedford, August 
26 (No. 1654). 
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