38o THE STORY OF PLANT LIFE 



stalk, not enlarged upwards. The parts of the flower 

 are in fours. The outer perianth-segments are 

 stalked, roundly rhomboidal. There are four stamens 

 in two whorls, and four carpels. The anther-cells 

 are not parallel. The anthers are stalkless and 

 from the connective a cup-shaped expansion like a 

 perianth-segment grows out. The fruit, a drupelet 

 or nut, is dry, large, keeled on the back when dry, 

 rounded when fresh, with a convex ventral margin, 

 green, slightly flattened, ovoid, straight, with three 

 dorsal ribs and a short beak. 



This is a floating plant reaching a length of several 

 feet, flowering in June and July, and is a herbaceous 

 perennial. 



The flowers rise above the surface of the water. 

 The stigma ripens first, and, as in other pondweeds, 

 the flowers are wind-pollinated. 



As the outer layer of the pericarp contains air, the 

 achene floats on the surface and is carried to a 

 distance, finally sinking when the air escapes. 



Batter-Dock, De'il's Spoons, Flatter-dock, Fish- 

 leaves, Water Spike, and Tench-weed are the names 

 applied to this species. The last name reminds the 

 fisherman that the Pondweed is an effective entangle- 

 ment preventing him very often from landing his 

 tench. 



PoTAMOGETON NATANS. — The Frontispiece gives a 

 good idea of the habitat of this plant and the social 

 habit, the plant being a floating-leaf type. 



