218 



LEMNACE^. 



[CLASS 



Type Lesser Duckweed (Lemna minor). 



A floating plant, consisting of minute green fronds 

 bearing flowers in fissures of their margins. 



The flowers are of extreme simplicity, consisting of a 

 small membranous spathe, enclosing 2 stamens and a 

 single carpel. Some regard each stamen as representing 

 a distinct male, and the carpel a female flower. 



Five species are native, one of which (L.pofyrfo'za)'ha.s 

 been very rarely (? but once) observed in flower in Britain. 



FIG. 164. Inflorescence of Duckweed. 



The flowers of the common species are frequently over- 

 looked, from their minuteness. 



Examine, with a lens, the tips of the slender roots of 

 any Duckweed. They are covered by a highly developed 

 modification of the cellular sheath, described at page 2. 



63. Natural Order Naiadese. The Pondweed Family. 



DISTRIBUTION. Cosmopolitan aquatics, occurring both 

 in fresh and salt water. British genera 5, species 14. 



Floating or submerged plants. Perianth o or 4-leaved. Pistil 

 apocarpous. 



Type Floating Pondweed (Potamogeton natans). 



An aquatic herb, with floating oblong or elliptical 

 op que petiolate stipulate leaves, and dense pedunculate 

 spikes of minute flowers. 





