102 Rhodora [Mav 
SOME VARIETIES OF POTAMOGETON AND SPIRAEA. 
K. M. WIEGAND. 
ACCORDING to Dr. Morong and other recent writers the typical form 
of Potamogeton Nuttallit should be small and slender with flattened 
stem, crowded distichous submersed leaves 2—7 inches in length by 
1-3 lines in width, linear and 5-nerved. The floating leaves should 
be small (1.5— 3.5 inches long x 4—12 lines wide), 12—27-nerved, ellip- 
tical and sloping at the base into a short petiole. Most of our speci- 
mens from New England and westward agree very closely with this 
description except that the submersed leaves are often 7-nerved and 
never over 4.5 inches long. 
My attention was recently called by Prof. W. W. Rowlee to some 
peculiar gigantic specimens collected by him in Oswego County, New 
York. Further investigation showed that this large form is frequent in 
ponds and streams throughout Central New York, and constitutes a 
quite well-marked variety. So far as known to me, it has heretofore 
been noticed only by Professor Dudley who, in the Cayuga Flora, says 
that ** Only the specimens from Cayuta Lake have the small leaves as 
described by Robbins." The Cayuga Lake plants are thus recognized 
as larger. 
'The new form differs from the type in having a much longer stem, 
more distant submersed leaves, which are always very much larger and 
broader, and have from 9 to 13 nerves. When in the water they are also 
not so conspicuously distichous. The floating leaves are larger and 
more inclined to be obovate, and the mature fruit is noticeably larger. 
Possibly the extreme length of leaf in Dr. Morong's description was 
taken from specimens of this form. The following is a brief charac- 
terization of the variety. 
P. NurrALLI1 Cham. & Schlecht. var Cayugensis. Large and stout, 
nearly a meter in length ; stem somewhat flattened, internodes usually 
long (2-15 cm.) ; submersed leaves not conspicously distichous, very 
large (12-22 cm. x 5-10 mm.), evenly linear, acute or obtuse, 9—13- 
nerved, the space between the two inner nerves reticulated as in the 
type; floating leaves, several pairs separated by long internodes, larger 
than in the type (blade 5—6 cm. x 2-2.5 cm.), obovate oblong or ellip- 
tical, 30-40-nerved, rounded at the apex, tapering below into the 
broad petiole which is 3.5-4 cm. long; peduncles stout, achenes larger 
(3.5 mm. diam.) ; embryo spirally coiled. 
