9- 



Fresh Water Aquarium 



the plant will remain green all through the 

 winter. It is quite valuable as an oxygen- 

 ator. 



Fig. 42. Shell Flower, Pistia stratiodcs. 



Shell Flower (Pistia stratiodcs) is a trop- 

 ical aquatic and needs a higher temperature 

 than we usually have in our rooms. Dur- 



