AQUATIC PLANTS OF FRESHWATER 



POTAMOGETON 



About 40 species and sub-species of Potamogeton, also known as 

 Channel, Pond or Riverweed, the latter from the Greek significance of 

 the botanical name, are native of North America. They are all weedy 

 plants which attach themselves to the bottom of ponds, shallow lakes, 

 streams and canals and grow so luxuriantly as to choke the waterways. 

 They are also known as Stink-grass on account of the rank fetid odor of 

 the plant when exposed to the sun on the banks or shore. In many of 

 the species there are two kinds of leaves, the narrow submerged and the 

 broader floating leaves, which surround the small green flowers consisting 

 of 4 stamens and usually 4 one-ovuled ovaries. The fruit is a small nut- 

 let containing a coiled or hooked embrio. Four species have come into 

 slight notice in American water gardens. 



Potamogeton crispus (Linn.) or Curled-leaved Pondweed, Fig. 128, has 

 a dark green stem and beautiful dark olive-green, two-ranked serrulate 

 and crisped linear leaves with a compound midrib and the outer nerves 

 near the margins. The ovoid fruit has a small embrio with its apex 

 pointed directly towards the base, and the peduncle or stem recurved on 



the fruit. It occurs generally in fresh, brackish 

 and salt water from Massachusetts to Pennsyl- 

 vania and In Virginia, and flowers in August. 



Potamogeton lanceolata (Linn.) or Spear- 

 leaved Channelweed or Pondweed, Fig. 128, is 

 generally distributed In all running and stagnant 

 waters, forming thick almost impenetrable mats 

 that obstruct the streams; and, as it is one 

 of the fragile species, it often occasions the stop- 

 page of turbines and water-wheels, especially in 

 the late fall when it sheds its foliage. In this 

 species the winter buds may be readily recognized. 

 The flowers appear In July and August and 

 consist of a cluster of tiny green pedals about a 

 thick scape and the fruit is a hard nutlet with 

 one or sometimes two grooves on the back; the 

 embrio forming a spiral of one and a half turns. 

 Native in almost all parts of the United States 

 and North America. 



Potamogeton natans (Linn.) or Common 

 FIG. ia8. Curled-leaved Pond- Spade-lcaved Floating Channelweed or Pondweed, 



weed, Potamogeton crispus^ and f ^ \ a .. • tU 



Spear-leaved Pondweed, Potamoge- Fig. 1 29, haS long and almOSt leatleSS StCmS Wlttl 



""'Tetre'dt^-rwrr''"'' short narrow pointed submerged leaves, rounded 



201 



