AQUATIC PLANTS OF FRESHWATER 



and 20 inches in length, having a tufted stem from a single root. The 

 jointed capillary leaves are often ij^ to 2 inches long and form in whorls 



of 8 to 1 1 . Quite common throughout America 

 on a sandy soil in shallow ponds and streams. 

 This plant is sometimes mistaken for Cerato- 

 phyllum, but does not form the thick branch- 

 ing clusters of the latter plant. 



Chara gymnopus (A. Br.) or Elegant Chara 

 is a slender hairy-stemmed plant growing to a 

 length of 2 feet in deep water and having the 

 verticils of many-celled capillary leaves sur- 

 rounded by a whorl of stipules. Each leaf 

 usually bears three spores. This beautiful 

 species is not uncommon, new localities coming 

 constantly into notice. 



Chara crinita (Wallr.) or Crumpled Chara 

 somewhat resembles N. tenuissima and has 

 rigid and erect stems and densely clustered, 

 fascicled hairlike leaves. The tiny spores form 

 in the axils of the leaves. Usually grows to 

 a height of 6 to 12 inches. It occurs more 

 usually in brackish water in the Eastern States, 

 notably in Massachusetts and New York. 



Nitella gracilis is a fine aquarium plant but 

 thrives so abundantly that it forms dense 

 masses impenetrable to fishes and snails. When introduced, it should 

 be kept down by frequently removing the excess growth. It is a good 

 oxygenator, as are all the vigorously growing submerged aquatics. The 

 Charas do not grow as well in the aquarium as the Nitellas. 



No other aquatics so plainly show the activity of plants in liberating 

 oxygen as this group, particularly Nitella. When the growth is dense in 

 strong sunlight, the oxygen bubbles form on the stems and leaves like 

 suspended clusters of tiny pearls or slender strings of transparent glass 

 beads; and when undisturbed, the plants appear as though hung with 

 jewels. It has been observed that the Paradise-fish seems to prefer this 

 .oxygen to breathing the air and will occupy itself for hours in taking them 

 into the mouth for gill absorption. 



Together with the Nitellas, Confervae and other large Algae are 

 usually introduced into the aquarium, the principal of these being the so- 

 called Frog-spittle, Nostocs and Zygnemae, hereafter more fully described. 

 These seem rather to be associated with the Characeas than parasitic, and 



FIG. 122. Slender Nitella, Nitella 



gracilis, attached to a water soaked twig, 



Reduced one-third. 



195 



