3o6 A GUIDE TO THE WILD FLOWERS 



'5^<3 



rity to float away after fertilizing the female flower. Through- 

 out North America, and introduced into England and the 

 Continent. Fig. 937. 



938. HoRNwoRT. Ceratophyllum dcmersmn. (Ceratophyll- 

 aceae.) A very slender submerged water plant with thread- 

 like leaves, Y^-iYi in. long, forked, the margins minutely 

 toothed or barbed. Flowers minute, solitary, stalkless at the 

 leaf-insertions, followed by a nut-like fruit about yi in. wide. 

 In slow streams or ponds, nearly throughout North America. 

 Fig. 938. 



939. Water Milfoil. Myriophyllum pinnatum. (M. scabra- 

 tum.) (Haloragidaceae.) A submerged aquatic, except for 

 the short spikes of flowers and a few leaves near them. Sub- 

 merged leaves in 3's or 5's, or even more crowded at each 

 joint, greatly divided into slender thread-like segments. 

 Flowers minute, in small often interrupted spikes that appear 

 above the surface. In ponds, Rhode Island to Florida, and 

 westward. Fig. 939. Several closely related species occur in 

 the area. 



940. PoNDWEED. Potamogeton perfoliatus. (Zaninchelli- 

 aceae.) A submerged aquatic except for the spikes of flow- 

 ers and fruit which appear above the surface. Leaves oval or 

 almost cup-shaped, about ^i in. long and wide, the stem 

 passing through the base. Flowers greeni^h^Jnconspicuous, in 

 small spikes, followed by tiny nut-like fruits. In ponds and 

 streams, almost throughout North America, Europe and Asia. 

 Fig. 940. One form of this is found also in brackish waters 

 along the coast. 



