366 THE STORY OF PLANT LIFE 



Fruit is not formed in this country and reproduc- 

 tion is mainly vegetative. 



Frog's Foot, Grayves, are names for the Duckweeds 

 generally, and the name cited is merely a book-name. 



No properties are known for these plants, except 

 that they afford food for water birds. 



Lemna trisulca. — In the illustration {Fig. loi) 

 the plant is seen to be of floating habit. The fronds can 

 be distinguished as proliferous at right angles, which 

 causes the chain-like arrangement. 



Rootless Duckweed {Wolffia arrhiza). 



In the first Latin name is commemorated the work 

 of a botanist, J. F. Wolff, who wrote on the Duck- 

 weeds in 1801. The second Latin name refers to the 

 absence of roots. 



Being the smallest flowering plant that is known 

 to science, it is not surprising that its distribution, 

 so far as ascertained, is limited, for it is probably 

 largely overlooked. It has been found in Kent, 

 Surrey, Middlesex, and Essex. 



Ponds and slow streams form the habitat of this 

 microphytic type. It occurs in the fresh-water aquatic 

 formation, in waters relatively rich in mineral salts, 

 in slowly-flowing streams in the floating-leaf associa- 

 tion. 



About the size of a grain of sand the fronds are 

 \ in. long by J in. broad, are thick, and swollen 

 underneath, sub-globular, linear, oblong, flat above, 

 loosely cellular below, cleft near the base, solitary 



