NUDIFLOR^ 367 



at the base. The young frond separates from within 

 the base of the old one, and is soon detached. The 

 walls of the epidermal cells are straight. 



The flowers are minute and break through the 

 upper surface of the frond. There is no spathe. 

 There is a single stamen. The anther is rounded, 

 stalkless, one-celled. The pollen is smooth. The 

 ovary is rounded, one-celled. The style is short and 

 the stigma flattened. There is a single erect ovule 

 which is orthotropous. The fruit is a spherical ovule 

 and indehiscent. The seed is oblique, with endo- 

 sperm that is fleshy and not abundant. 



The height of this diminutive floating plant is 

 negligible. It flowers (not in the British Isles) in 

 June and July. Propagation is by offsets as above, 

 in this country. 



If fruit is formed it is dispersed by the agency of 

 water. 



By reason of the existence of only one anther and 

 the flowers being produced on the surface of the 

 frond, not in a slit at the margin, the plant (formerly 

 grouped with the other Duckweeds as Lemna 

 michelii), is included in a separate genus, Wolffia, 



WoLFFiA ARRHIZA. — The illustration {Fig. 102) 

 serves to give some idea of the size of the plant, which 

 consists merely of a frond y without any roots. 



