APOCARPE^ 381 



Horned Pondweed (ZannichelUa palustris). 



This plant is named in honour of a Venetian apo- 

 thecary and botanist, John Jerome Zannichelh, who 

 wrote a history of the plants of his district, and died in 

 1729. The second Latin name is intended to indicate 

 the habitat, but the plant is truly aquatic, and not a 

 marsh plant. In the English name the horned fruits 

 are referred to. 



Frequent in most parts of the British Isles up to 

 the Orkneys the Horned Pondweed is found less 

 frequently in the west of Scotland where there is less 

 aquatic vegetation. It occurs in Ireland and the 

 Channel Islands. 



Ditches and fresh-water ponds, lagoons, or stagnant 

 water, streams, etc., are the habitat of this species. 

 It is found in the fresh-water aquatic formation in 

 waters relatively rich in mineral salts, in stagnant 

 waters in the submerged-leaf association. 



In habit this plant is of the Pondweed type. The 

 stem is slender, bristle-like, branched, the branches 

 spreading, submerged. The leaves are opposite, 

 slender, thread-like, linear, more or less whorled, 

 bright green. There is a small sheathing mem- 

 branous stipule embracing the stem. 



Being a monoecious plant, the male and female 

 flowers are separate. The female flower is terminal, 

 the male arising from the axil of a lower bracteole, 

 and from the axil of the upper bracteole a new branch 



