17 
alternate, ovate or roundish-ovate, sometimes large oval or nearly 
orbicular, subcordate, 2-4% inches long and 9 lines to 314 inches 
broad, 25-33-nerved. Petioles about as thick as the stem, 2—4 
inches long, and spotted like that. Submerged leaves of 2 kinds, 
the uppermost pellucid, lanceolate, long-acuminate, undulate, 3-8 
inches in length, 6-18 lines in width, tapering at the base into a 
short petiole, 10 to 20 nerved, irregularly cellular-reticulated for a 
narrow space on each side of the midrib; the lowest near the base 
of the stem, fewer, much thicker, opaque, spatulate, oblong or 
ovate, with a rounded, tapering base, on petioles which are often 
broadened and ¥ to 4 inches in length. The submerged leaves 
are usually much decayed at the time of flower and fruit, and, in 
order to get them in good condition, they must be gathered be- 
fore the flowering period. Stipules obtuse or long-acuminate, bi- 
carinate. Peduncles slightly thicker than the stems, 2 to 4 inches 
long. Spikes about an inch in length and densely fruited, when 
fruiting at all. Fruit tapering at top into a stout apical style, 2 
lines or a little more in length and 1:4 lines in breadth, thick and 
turgid, the back sharply 3-keeled, middle keel prominent, largely 
rounded at base; face angled near the centre, with a sinus below; 
embryo coiled 1% times. Aberrant forms with coriaceous sub- 
merged leaves, and the floating ones with slender petioles, 10 or 
more inches long, are found in mill ponds where the water has 
been drained off and the pond refilled. It occurs sometimes, also, 
in very deep water, when the upper part lengthens into slender 
simple or long, branching stems, very different in appearance from 
the shallow water forms. It may also be found quite often in 
an amphibious state in pools which have become nearly dry, when 
it is almost without stem and exhibits coriaceous leaves only. 
An endemic species, rare, and still more rarely found in fruit. 
The most abundant locality in which I have observed it is on the 
island of Nantucket, where it nearly fills some of the small ponds, 
and fruits quite freely. 
Ponds, in Wells, Me. (Harvey), Brattleboro, Vt. (Frost), East- 
ern Massachusetts to Pennsylvania, Georgia, and near St. Louis, 
Mo. (Engelmann). June, July (Plate XXVIII). 
