LAKE TO FOREST OR PRAIRIE 



237 



P. pectinatus is entirely below water. Its leaves are long and 

 narrow and are provided at the base with stipules which unite 

 with the base of the leafstalk to ensheath the stem. Tape grass 

 or eel grass has long, ribbon-like, narrow leaves, entirely below 

 water or at times with the tips floating. The blossom is borne 

 on a string-like stalk that is coiled at first to hold the bud below 

 the surface and that uncoils and lets the blossom to the surface 

 only while it opens long enough to permit of fertilization. 



336 



337 



338 



Figs. 336-338: Fig. 336. — Bur reed, Sparganium eurycarpiim; Fig. 337. — 

 Arrowhead, Sagittaria latifolia; Fig. 338. — AMld rice, Zizania aquatica. 



Then comes the water lily zone with water shield, Brassenia 

 purpurea; lotus, Nelumho; yellow and white water lilies. 



Shoreward still farther comes the bulrush zone (Fig-. 335), 

 with Scirpiis lacustris, S. validus, S. atrocinctus, S. americanus , 

 S. TorreyiyS. atrovirens (Fig. 327), and other species; rushes of 

 the genus Junctis like /. halticus littoralis; spike rushes like 

 Eleocharis acicularis, E. palustris, etc. The bulrushes have, as a 

 rule, long, tapering, solid round leaves sheathed at the base. 

 The inconspicuous perfect flowers are borne in spikelets that are 

 in some species solitary, in others clustered near the end of the 

 leaf. Torrey's rush (Fig. 328) and the American rush are the only 

 common ones in our neighborhood that have sharply triangular 



