244 
all pinnatifid with hair-like divisions, subverticillate or scattered. 
It rarely flowers or fruits, and when it does the inflorescence may 
be seen scattered here and there in the axils of the leaves. One 
or more of the forms occur from eastern Massachusetts to Mary- 
land and Tennessee, and west to Illinois and Indiana. 
6. M. proserpinacoides. Gill. in Hook. Bot. Misc. 3, 313. (1833). 
This is a South American species introduced from Chili or 
Buenos Aires, where it is a native. It has partially naturalized 
itself in Hopkins’ pond, near Haddonfield, and other places in 
New Jersey, and seems to be spreading. All the plants occurring 
in our waters appear to have sprung from stock imported several 
years ago by the florist, Mr. E. D. Sturtevant, of Bordentown, 
New Jersey, who writes that “it is entirely hardy here, below 
the reach of ice or frost.” 
Hooker describes it as monoecious and dicecious. I have 
seen only pistillate plants. These are very vigorous, 10 to 40 
cm. high, even lifting themselves out of the water and growing 
quite as well above as below it. Normally, however, it seems to 
be a submerged plant. Leaves all alike, smooth, glaucous, pectin- 
ate-pinnatifid, in crowded verticils of fives, 15 to 20 mm. long, 
pinne linear, twenty to twenty-five in number, the pairs opposite 
or subopposite, each segment about 5 mm. long, and sharply 
pointed. Stamens said by Gillies to be eight. _Pistillate flowers 
axillary, about 1 mm. high, without petals, with four white plu- 
mose stigmas. Fruit not seen, but as indicated by the ovaries, 
the carpels should be smooth. Between the bases of the leaves 
-and among the flowers are many small white trichomes, or hair- 
like bracts. 
7. M. heterophyllum. Michx. FI. 2, 191 (1803). 
Potamogeton verticillatum. Walt. Fl. Car. 90 (1788). 
Floral leaves in whorls of threes and fives, linear, ovate or 
lanceolate, serrate or rarely entire, much longer than the flowers, 
sometimes as much as 18 mm. in length and 4 mm. broad ; sub- 
merged leaves verticillate or subverticillate, crowded, about 2 cm. 
long, with six to ten pairs of capillary pinne. The flowering 
spike occasionally attains the length of 40 or 50 cm. Petals 
somewhat persistent. Stamens four, very rarely six. Fruit 2 
