76 
28. Potamogeton gemmiparus (Robbins) Morong. 
(Fig. 
Potamogeton pusillus var. (?) gemmiparus Rob- 
bins in A, Gray, Man. Ed. 5, 489. 1867. 
Potamogeton gemmiparus Morong, Coult. Bot. 
Gaz. 5:51. 18 
Stems filiform, terete, branching, 5/-4° 
long. Leaves capillary, sometimes not as 
wide as the stem, often with no perceptible 
midrib, tapering to the finest point, 1/—3/ 
long, 2-glandular at the base; stipules %4/-1/ 
long, acute or obtuse, mostly deciduous; 
spikes interrupted, 3-6-flowered ; peduncles 
filiform or sometimes slightly thickened, 
14/-2/ long ; fruit seldom formed, similar to 
that of P. pusillus, except that it is flatter 
and somewhat impressed on the sides. 
In ponds, eastern Massachusetts and Rhode 
Island, It is commonly propagated by its abun- 
dant buds, the leaves and stems are often alike 
in thickness so that the plant seems to consist 
of threads. Aug.—Sept. 
29. Potamogeton diversifolius Raf. 
In still water, Maine to Florida, west to Nebraska and Texas. 
Potamogeton diversifolius multidenticulatus Morong, Mem. Torr. Club, 3: Part 2, 48. 
NAIADACEAE. 
Capillary Pondweed- 
169. ) 
Rafinesque’s Pondweed. 
(Fig. 170.) 
Potamogeton hybridus Michx. Fl. Bor. Am. 1: 
101. 1803. Not Thuill. 1790. 
Potamogeton diversifolius Raf. Med, Rep. (II. 
53354. 1808. 
Stems flattened or sometimes terete, much 
branched. Floating leaves coriaceous, the 
largest 1’ long by 1%’ wide, oval or elliptic 
and obtuse, or lanceolate-oblong and acute ; 
petioles generally shorter, but sometimes 
longer than the blades, filiform or dilated ; 
submerged leaves setaceous, seldom over 
4 /’ wide, 1/-3/ long ; stipules obtuse or trun- 
cate, 3’’-5’’ long, those of the floating leaves 
free, those of the submerged leaves some- 
times adnate; emersed peduncles 3//-7’’ 
long; submerged peduncles 2//-3’’ long, 
clavate, as long as the spikes; emersed spikes 
3/’-5”’ long, occasionally interrupted ; fruit 
cochleate, rarely over 4’’ long, 3-keeled, 
the middle keel narrowly winged and usu- 
ally with 7 or 8 knob-like teeth on the mar- 
gin, the lateral keels sharp or rounded; 
embryo coiled 1'% times. 
June—Sept. 
1893. 
Differs from the type in the numerous teeth of the fruit, as many as 12 being sometimes found 
on the middle keel, and each lateral keel with 6-8 more, the teeth often bristle-like and sometimes 
2-pronged. 
Potamogeton diversifolius trickophyllus Morong, Mem. Torr. Club, 3: part 2, 49. 
Connecticut to eastern Pennsylvania and Delaware. 
1893. 
Plant about 6’ long, without floating leaves, the submerged leaves as fine as floss silk and 
entirely nerveless. Lake Marcia, New Jersey. 
