123 
1068. P. zizia, Mertens & Koch. 
P. lucens , L., var. minor , Nolte. 
Eastward from South Chicago, having about the same range there 
as P. lucens, and as common, especially at Pine Station, Ind. 
August — September. (B. P.) 
Late in the season the plant sends up branches bearing immersed 
and shining leaves, by the lengthening of the stem beyond the 
earlier emersed ones, that at this time are submerged. (B. P.) 
1069. P. lucens, L. 
Throughout but infrequent, most common in ponds and small lakes 
of the Calumet Region from South Chicago eastward. August — 
September. 
“Skokie.” Cheltenham Beach. Riverside, University of Chicago 
Herbarium. 
1070. P. perfoliatus, L., var. lanceolatus, Robbins. 
Common in Calumet river and in lakes and ponds southeast of 
Chicago. July — October. (B. P.) 
Quite variable in the length of the leaves, from 1^ to 3| inches, those 
of the lower part of the stems are commonly shorter. All the 
plants collected from this vicinity, and nearly all throughout the 
West, are of the yariety, and not of the type. 
1071. P. ZOSteF88foliuS, Schum. 
P. compressus , Fries. 
Infrequent. June — August. (B.) 
Calumet river and ditches entering it. South Chicago. 
1072. P. paueiflorus,* Ph. 
Very common throughout, in shallow water of pools and ditches. 
f June — September. (B) 
Perfect fruit is sometimes found in the early part of June. Peduncles 
short, spikes capitate, 2 to 8 flowered. The forms in our vicinity 
nearly all approach the following variety, generally being plainly 
3-nerved. 
*This species, like several other Potamogetons, is quite variable, and the 
type and variety imperceptibly grade into one another. It sometimes occurs 
with hair-like stems, barely a foot in length, and with fine, short leaves, 
(Manistee, Mich.), or with stems 2 to 4 feet long, and with leaves 3 to 5 nerved, 
(as in the rapid water of the Pine river, at Poysippi, Wis.), where it is var. niaga- 
rensis. Those found in our limits are somewhat intermediate, the extremes of 
size not yet having been seen. None of the forms collected by us at the West 
exactly agree with the type of the var. niagarensis, which grows in the mill race 
at Niagara Falls, near the Cataract House. 
