55 
1880 Mr. Е. Faxon had the good fortune to secure а few fruiting 
specimens in Jamaica Pond, Mass. Besides them I have never 
known another instance, although the plant is very prolific in the 
localities where it occurs, sometimes densely covering the bottoms 
of ponds for acres. Mature fruit obovate, about 2 lines long by 
11% lines wide, 3-keeled on Ше back, the middle keel sharp and 
prominent, the laterals rounded ; face arched; sides with a shallow 
depression which runs into the face below the arch; style sub- 
apical, thick, slightly recurved, obliquely truncate; apex of the 
embryo pointing slightly inside of the basal end. 
So far as known, confined to the northern part of North 
America. New Brunswick, Ontario, Lake Superior (Macoun) ; 
New England to Northern New Jersey, and westward to Oregon 
(Hall, Wilkes’ Exploring Expedition). (Plate LXI.) 
$- RUPPIA, L. Sp. PL 127 (1753). 
Stems capillary, widely branched. Leaves very slender, alter- 
nate, 1-nerved, tapering to an acuminate point, with a membranous 
sheath at the base. Flowers on a capillary, spadix-like peduncle, 
naked, perfect, consisting of two sessile anthers, each with 2 large, 
separate cells, attached by the back to the peduncle, having be- 
tween them several pistillate flowers, in 2 sets, on opposite sides 
of the rachis, the whole at first enclosed in the sheathing base of 
the leaf; stigmas sessile, peltate. In the development, the stami- 
nate flowers drop off, and the peduncle elongates, bearing the 
pistillate flowers іп two clusters at the end. The flowers are ferti- 
lized above water, after which the peduncles coil up and are drawn 
beneath the surface. Fruit a small, obliquely pointed drupe, several 
in each cluster, pedicelled; embryo oval, the cotyledonary end in- 
flexed, and both that and the radicle immersed. 
Half a dozen or more species have been enumerated, but prob- 
ably all may be reduced to two or three. In salt, brackish and 
fresh waters throughout the world. 
1. Ruppia MARITIMA, L. Sp. Pl. 127 (1753). 
Stems often whitish, 2 or 3 feet high, the nodes irregular, 
naked, 1-3incheslong. ‘Leaves 1-3 inchesin length and % line or 
less in breadth ; sheaths membranous, 3-4 lines long and with a 
minute ligule or short free tip at the top. In fruit the peduncles 
