52 
ripening 2 to 8 seeds, in a verticil. Fruit roundish obovate or 
obliquely obovate, with a thick hard shell, 1%-2 lines long and 
1-1 Y lines wide, without a middle keel, but with obscure lateral 
ridges on the back, plump on the sides, and curved, occasionally 
a little angled on the face; style distinct, straight or recurved, 
facial; embryo apex nearly touching and pointing directly towards 
the basal end. In American plants, the keels are generally ob- 
scure and often obsolete, and the fruit more nearly approaches 
that of fliformis in size. 
This species is frequently propagated by root tubercles which 
are nearly as large as peas and lie imbedded in the mud through 
the winter. In this state they are eaten by wild fowl, and the 
crops of these birds are often filled with them. 
P. pectinatus and P. filiformis are often confounded, and in 
the absence of fruit it is impossible in all cases to make sure of 
the species. As a general rule P. filiformis is a smaller plant. 
In regard to the fruit, that of P. pectinatus may always be known 
from formis by its distinct and often recurved style, and usually 
itis larger. Both species occur in brackish water, sometimes in 
tidal and salt water, and also very extensively in fresh water. 
Ponds and rivers. Widely distributed in Canada from Cape 
Breton to British Columbia and northwards (Macoun). In the 
United States it ranges from New England to Florida and Texas, and 
across the continent to Oregon and California. Lower California 
(Orcutt, Palmer). Southern Mexico (Helmsley). Cuba (Wright). 
A world-wide species, occurring in Europe, Australia, Africa and 
Asia. (Plate LVIII.) 
35. PorAMOGETON LATIFOLIUS (Robbins) Morong. 
P. pectinatus,* var. (? ) latifolius, Robbins, Bot. King's Ex. 338 
(1871). 
Stem stout, white, branching, 2-3 feet high. Leaves numer- 
ous, flat, 1-3 inches long and 1-2 lines broad, 3-5 nerved, reticu- 
late with many cross veins, obtuse or abruptly apiculate, the nar- 
rower ones acute. The part of the stipule adnate to the leaf, broad, 
many-nerved, scarious-margined, 17-1 inch long, the free portion 
shorter. Peduncles 1-3 inches long. Spikes interrupted. Mature 
fruit much like those of pectinatus, while the foliage differs greatly. 
