AQUATIC PLANTS OF FRESHWATER 



smaller elong-ovate leaf and grows in closely matted clusters of dull green 

 color. L. gibba has a flat leaf, the larger about Y^ 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. trisulca is a pond variety with the serrated ^ 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 

 on account of its quaint appearance, having no merit 

 as an oxygenator. Another very similar species is 

 J. filiculodes, a northern variety. 



FIG. 134. Floating 



Pondmoss, Azolla 



caroliniana. 



CRYSTALWORT 



Two species of Crystalwort, Riccia fluitans and R. nutans. 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 ^ 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 

 the aquarium, but as it is brittle and the fishes break 

 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. 



FIG. 135. Crystalwort, 

 Riccia fluitans. 



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