406 WILD FLOWEKS OF 



Arrowhead (Sagittaria sagittifolia) lifts its singular- 

 shaped leaves and purple flowers, creeps on beneath 

 the flickering shade of pallid lank-leaved osiers scat- 

 tering a plumy waste of feathery seeds, and reluc- 

 tantly advances towards the polluting suburbs of the 

 town that soon blackens its current and chars the 

 stunted alders clinging to its margin. 



Solitary stagnant ponds and wide drains and ditches 

 that occur in flat marshy places, appear about this 

 time quite green with a close investing coat of Duck- 

 weed that covers them like a carpet. In the genus 

 Lemna the term frond is given to what appears to be 

 stem and leaf united in a fleshy peltate cellular disc. 

 The increase of the plants appear to be principally by 

 gemmce growing out of the sides of the parent frond, 

 and thus forming dense proliferous masses that 

 speedily cover in the decline of summer the entire 

 surface of a pool or ditch. The young plants throw 

 out roots, and then separate from their parent to 

 increase and multiply in a similar manner. This 

 " green surface of the stagnant pool" harbours great 

 quantities of aquatic insects, as well as Moluscce, 

 Vermes, &c. and ducks consequently delight to explore 

 its recesses, soon clearing a pond of its verdant invest- 

 ment. Where it is very thick in unfrequented marshy 

 spots, its surface may be often seen marked with 

 indented criss-cross lines from the "Water Shrew or 

 Vole, who loves to paddle through it in the twilight 

 to seize the Lymnece or Water-slugs there ; or some- 

 times the rough head of the Water Eat may be seen 

 peering from, among it. 



While on the margin of the commony waste, where 

 some old timbered farm-house, with its thatched barns, 



