644 NAI ADAGES 



ORD. XCVIIL NAIADACKE. POND-WEED 

 TRIBE. 



Submersed or floating aquatics with very cellular 

 stems and peculiar leaves, which are sometimes almost 

 leathery, but more frequently thin and pellucid. The 

 flowers are small, olive-green, resembling in structure 

 the Arrow-grasses ; sometimes solitary, but more fre- 

 quently arranged in spikes, they inhabit ponds and slow 

 streams, or rarely salt marshes. One British species, 

 Zoster a marina, grows in the sea. 



1. POTAMOGETON (Pond-weed). Flowers in a spike ; 

 stamens and pistils in the same flower ; perianth of 4 

 sepals ; stamens 4 ; carpels 4, sessile. (Name from the 

 Greek potamos, a river, and geiton, a neighbour.) 



2. EUPPIA. Flowers about 2 on a stalk ; stamens 

 and pistils in the same flower \ perianth ; stamens 4 ; 

 carpels 4, at first sessile, afterwards raised each on a 

 long stalk. (Named in honour of H. B. Euppius, a 

 botanist of the 18th century.) 



3. ZANNICHELLIA (Horned Pond-weed). Flowers 

 axillary ; stamens and pistils separate (monoecious) ; 

 stamen 1 ; carpels 4. (Named in honour of J. J. Zanni- 

 chelli, a Venetian botanist.) 



POTAMOGETON NATANS (Floating Pond-weed] 



