
AQUATIC PLANTS OF FRESHWATER 
it has taken the place of Watercress. It should be introduced in loose 
bunches as it requires strong light to grow submerged and makes a good 
screen for the fishes. The dark-green, almost circular leaves with their 
straight stalks strive to reach the surface and give a vigorous thriving 
appearance to the plant, in fine contrast with the languid appearance of 
the usual aquatic plants in the aquarium. 
CALLITRICHE 
The Water Starwort family contains a number ot 
herbaceous aquatic and semi-aquatic species, with 
slender stems, opposite spatulate leaves and minute 
axillary flowers, of which the following are native 
American species :— Callitriche verna or C. palustris, 
Vernal or Spring Water-Starwort, Water Fennel; Fig. 
130, C. difda, Autumnal or Northern Water-star- 
wort; C. heterophyllum, Larger Water-starwort and 
C. austenii, Terrestial Water-starwort. They are 
pond or basin plants but generally will not thrive in the 
aquarium. 
Callitriche verna(Lindl.)is probably the hardiest, from 
the aquariist’s point of view, and is the most common and 
generally distributed species in cold or running water 
throughout the United States and Canada. It grows in 
the mud with elongated one-nerved spatulate submerged 
leaves and most peculiar floating leaves; which, though a 
moderate distance from each other are arranged to form 
a rosette, as the stalks of the lower leaves are longer than 
those near the apex and bring the floating leaves into 
clusters of 4’s, 6’s and 8’s. The small axillary flowers reach 
above the surface of the water and bloom from July to 
September. Native or wherever introduced, it spreads 
so rapidly as to become a nuisance, and should not be 
used in lily-ponds. Water Starwort is introduced into the 
FIG. 130. Spring Water- aquarium in small bunches, but either so or floating on 
starwort, Ca/latriche verna. 
Reduced one-third. the surface is eagerly eaten by goldfishes. 

UTRICULARIA 
The Bladderworts are divided into aquatic and marsh species, floating 
free or rooted in the mud. The aquatic species have finely divided leaves 
covered with minute bladders, the marsh species rootlets under ground 
and bladder-bearing leaves. There are about 150 widely distributed 
204 
