THE DUCKWEED TRIBE. 249 



& 3. h.). It may be separated with care into three 

 carpels, at the bottom of each of which lies a single 

 erect ovule, a great deal smaller than the cavity in 

 which it is placed {fig. 3.). The fruit is a narrow 

 three-cornered dry case, which divides into three 

 slender parts, each of which is partly filled with a 

 taper seed {fig. 70' ^^ almost all Monocotyledonous 

 plants, a considerable quantity of albumen is provided 

 for the nutriment of the young embryo, but the Ar- 

 roiv-grass tribe is one of those which form an excep- 

 tion to this rule. The embryo of these plants lies 

 immediately below the seed-coat, and consists of a co- 

 tyledon {fig. 8. c), having near its base a small slit 

 («.) through which the young stem is protruded when 

 the plant begins to grow. 



It is evident that this kind of structure is so unlike 

 what we find in the Bullrushes, as to require no 

 further explanation. What does require elucidation 

 is the reason of the singular arrangement of the 

 anthers, which I have just described ; it does not at 

 all appear for what cause they are so carefully embo- 

 died in two hollows of the calyx and corolla, nor 

 indeed how, under such circumstances, their pollen 

 is ever to reach the stigma. I must confess my inabi- 

 lity to explain the matter : you cannot do better 

 than reflect upon it, until you hit upon some solution 

 of the mystery. 



Far more simple than the previous tribes is that to 

 which the Duckweed (Lemna) gives its name. In the 

 former, whatever deficiency there might be in the 

 parts of fructification, there was at least a stem and 



