
AQUATIC PLANTS OF FRESHWATER 

scape of about their own length, with recurved stigmas. Only one species 
is known in the United States, which occurs in shallow streams from 
Massachusetts to Northern New York, Ontario and Minnesota to Georgia, 
Alabama and Kentucky. Flowers July and August. 
A few stalks of Ceratophyllum make a fine appearance in the aquarium, 
as the growth there developed is more delicate, brighter green and finer in 
appearance than that of the ditch, pond or stream. 
HIPPURIS 
This genus consists of a small group of aquatic herbs with simple 
erect stems and verticillate entire leaves, small axillary flowers and a one- 
celled, one-seeded fruit. There are three known species native to north 
temperate and lower arctic regions and southern 
South America. 
Hippuris vulgaris (Linn.) or Bottle Brush, 
Joint-weed, Mare’s tail, etc., Fig 126, has a slender 
stem and linear or lanceolate acute leaves in crowned 
whorls or verticils. The flowers have stamens with 
a short thick filament, comparatively large two- 
celled anthers and ovoid seeds hollow in the interior. 
The plant is native to swamps and bogs in Labrador 
and Greenland to Alaska; south to Maine along the 
shore of Lake Superior, in the Rocky Mountains to 
New Mexico and along the Pacific Coast. 
Hippuris tetraphyllum (Linn.) H. maritema 
(Hell.)or Four-leaved Mare’s tail, is a smaller species 
with obovate or oblanceolate entire leaves in verticils 
of 4’s and 6’s at the base of the stem. Native to 
Labrador and Canada to the United States border 
and in Alaska. 
Hippuris has the character of Amacharis cana- 

a een densis, but is larger, stiffer and more erect, growing 
12 to 15 inches above the water. It largely takes 
Hippuris vulgaris, and enlarged the place of Anacharis in northern waters and was 
AX 
TPAS 
~ 
FIG. 126. Mare’s Tail, 
fruit. Reduced one-half. : z - 
introduced into the Middle States by aquarium 
fanciers in 1898, but has recently been superseded by 4. canadensis gigantea. 
; FONTINALIS 
This genus of aquatic moss contains a quite considerable number of 
universally distributed freshwater species, two or three of which thrive in the 
aquarium. Ten species are recognized as native to the United States and 
199 
