AQUATIC PLANTS OF FRESHWATER 



will develop even after the larger plants have been cleaned before intro- 

 duction into the aquarium.- The dense growth probably acts as a shelter 

 for these film-like algae or more secure anchors for their development. 



ANACHARIS 



This mosslike aquatic plant is variously known to botanists as 

 Anacharis, Philotria or Elodea and commonly as Waterweed, Ditchmoss, 

 Water Thyme, Water Pest and in the British Isles as Babington's Curse. 

 There are 4 or 5 very similar American species 

 which bloom from May to August, but are also 

 propagated by a plentiful production of off- 

 shoots which, attached or separate, rooted or 

 floating, grow with amazing rapidity inanyditch^ 

 stream or pond throughout the United States 

 and North America except the extreme north. 

 It is a slender wholly submerged plant with 

 fragile jointed and branching stem, 4 inches to 

 3 feet long, dependent upon the depth of water, 

 so weak that it mats together and decays when 

 the water is withdrawn. The male and female 

 flowers are borne on separate plants. The pistil- 

 late flowers are raised to the surface by their long 

 calyx tubes and the minute staminate flowers 

 break off and rise to the surface to shed their 

 pollen. The fruit ripens below the surface of 

 the water. The plant also forms heavy buds 

 in the Fall, which drop to the bottom and 

 develop in the following Spring. It is a verit- 

 able pest, as it chokes up canals and waterways. 



Anacharis canadensis {Mich.) A. alsinastrum 



/^RaK \ R"irr Toi io <-Ua r,r^a,~'.a„ .« „ i. II FIG. 123. Ditchmoss or Anacharis, 



(bab.), ±<ig. 123, IS the species most generally ^.«.w ..w««.,. also a modified 

 to be found and has a weak jointed stem with *°™^"<"=^^". Reduced one-founh. 

 the leaves in whorls of 4's to 8's or the lower leaves opposite, linear and 

 minutely toothed. The white pistillate flowers develop on calyx tubes 

 from 2 to 12 inches long. 



The Common Anacharis A. canadensis. Fig. 123, thrives fairly well in 

 the aquarium, is a good oxygenator, but is so weak and fragile that it will 

 easily break into sections. It should be planted in the sand or pebbles in 

 groups of 4 to 10 stalks. Freshwater fishes and goldfishes feed upon the 

 leaves and in the aquarium frequently entirely destroy the plant. When 

 found in cold water streams the plants are more robust and the leaves 



196 



