
AQUATIC PLANTS OF FRESHWATER 

smaller elong-ovate leaf and grows in closely matted clusters of dull green 
color. JL. gibba has a flat leaf, the larger about 3¢ inch diameter, of a 
bright green color, to each of which is attached a single root. 
L. polyrhiza has the leaves of varying outline, densely clustered 
and overlapping each other, of varying shades, from pea-green to light 
olive-green. L. frisulca 1s a pond variety with the serrated 3, inch leaves 
of a light green color, which grow most oddly at right angles to each other. 
It is restricted to some few localities. 
All the duckweeds have tiny white flowers but during warm weather 
increase rapidly by offshoots from the edges of the leaves. In the aquarium 
goldfishes feed on their roots and leaves and soon destroy them. They 
_are to no purpose as oxygenators. 
FLOATING PONDMOSS 
This beautiful many-branched mosslike floating plant, known botan- 
ically as Azolla caroliniana, Fig. 134, consists of clusters of tiny bright 
red or reddish-brown leaves usually bordered with dark 
green, and having short roots under the centre of the 
fonts. In warm weather it occurs on slow-flowing 
streams and ponds in the Eastern and Middle States, 
but is more generally distributed in Southern waters. 

It does not thrive indoors in the aquarium and is prized 
FIG. 134. Floating : : : : 
Pondmoss, Azo//a on account of 1ts quaint appearance, having no merit 
caroliniana. 
as an oxygenator. Another very similar species is 
A. filiculodes, a northern variety. 
CRYSTALWORT 
Two species of Crystalwort, Riccia fluitans and R. natans, Fig. 135, 
are sometimes introduced into the aquarium. They are bright-green 
mosslike plants growing on the surface of still water, 
of which the first is the most common form and may 
be found in many coldwater ponds and streams. It 
has repeatedly forked, threadlike leaves, of which the 
segmented branches grow about % to 34 inch in 
length; and the second has clusters of heart-shaped 

leaves with several pendant rootfibres. It is a native 
of Southern waters. R. fluitans thrives fairly well in FIG. 135- v acre 
the aquarium, but as it is brittle and the fishes break Pa 
it, it soon floats on the surface in fragments or sinks to the bottom to 
clog the roots and stems of other plants. It has no merit as an oxygenator. 
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