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serve to nourish the young plant. They seem especially numer- 
ous on the broad-leaved forms, and may take the place of fruit. 
Irmisch in his work (Ueber einige Arten aus der natiirlichen 
Pflanzenfamilie Potameen, Berlin, 1858) gives a good description 
of them, with excellent figures, in an elaborate account of P. pec- 
tinatus. He compares these tubers or bulbs (Knolle) to those 
of Crocus and Gladiolus, and in their function of propagating the 
species to those of Scirpus maritimus and Cyperus esculentus, 
among Monocotyledons, and among Dicotyledons to the tubers of 
the potato and Stachys palustris. 
Note. — Some species of the genus are found just beyond our limits, in Cedar 
Lake, Ind., and are likely to be found within them. These are P. robbinsii, 
Oakes, and P. praelongus, Wulfen. There are some indications of P. vaseyi, 
Bobbins, having been found at S. Chicago, but as the specimens were imperfect, 
and not accessible now, or perhaps not in existence, it is deemed best to omit it. 
Aside from those given, and included in this note, no others are reported growing 
nearer than McHenry Co. , that touches Cook County at the northwest corner. 
P. vaseyi (its original locality), P. spirellus, Tuckerman and P. rufescens, 
Schrader, are all reported from that county by Dr. George Yasey, and may be 
looked for in the neighboring parts of Cook County. P. illinoiensis, Morong, 
may also occur here, as we find specimens of P. amplifolius with branching 
stems, but as it is a doubtful species at best, it may not be easy to establish its 
presence here. 
ZANNICHELLIA, Micheli. 
1077. Z. palustris, L. Horned Pondweed. 
Pond near Cheltenham Beach; rare. July 16, 1888. (Form with 
fruit nearly sessile.) The form with peduncled fruit is more com- 
mon, but intermediate forms occur, so that the distinctions on 
which var. pedunculata, Gray, are founded do not hold. Abundant 
in ditches at S. Chicago. Throughout in shallow water, but not 
abundant. July. (B.) 
NAIAS, L. 
1078. N. flexilis, Rostk. Schmidt. Naiad. 
Ponds, shallow streams and lakes; common, especially in the 
Calumet Region. July — Aug. (B.) 
CYPERACE^E. 
CYPERUS, Tourn. Cyperus. Gilingale. 
1079. C. flavescens, L. 
Evanston, Johnson. (B. P.) 
| 1080. C. diandrus, Torr. 
Low grounds ; frequent southward, less frequent elsewhere. Aug. — 
Sept. CU •; 
Abundant, especially south, Babcock. 
1081. C. diandrus, Torr., var. eastaneus, Torr. 
With the type; infrequent. (B. P.) 
