KEY FOR JUNE TO NOVEMBER 



144 a Flowers V in. or more broad on stout stalks i in. or 



more long Batrachium. p 154 



b Flowers less than a /4 in. broad 145 



145 a Leaves pinnately divided, the terminal segment largest 



Roripa. p 158 



b Leaves dissected into very narrow segments, the ter- 

 minal segment not the largest 146 



146 a Submerged leaves rigid, comb-like, alternate 



Proserpinaca. p 190 

 b Submerged leaves not rigid, usually in whorls 147 



147 a Leaves in whorls of 3-5 ; flowers in spikes 



Myriophyllum. p 190 

 b Leaves in whorls of 5-12; flowers in the axils of the 



leaves Ceratophyllum. p 151 



148 a Leaves linear, usually i in. or less broad 149 



b Leaves not linear, usually % in. or more broad 157 



149 a Flowers in globose heads; leaves 10 in. or more long 



Sparganium. p no 



b Flowers not in globose heads 150 



150 a Flowers in woolly heads; leaves basal. .Eriocaulon. P 132 

 b Flowers not in woolly heads; leaves not all basal .... 151 



151 a Leaves 5 in. or more long, grass-like 152 



b Leaves 3 in. or less long 154 



152 a Plant growing in fresh water; spike of flowers i in. 



or less long Vallisneria. p 112 



b Plants growing in salt water or on salt marshes 153 



153 a Leaves i-veined Zannichellia. p in 



b Leaves 3-7-veined Zostera. p in 



154 a Leaves mainly alternate, not in whorls. .Potamogeton. p no 

 b Leaves opposite or in whorls 155 



155 a Leaves with sheathing petioles or sheathing stipules 



Naias. p in 

 b Leaves not with sheathing petioles or sheathing stipules 156 



156 a Leaves usually in whorls of 3 or more, all linear 



Ptrilotria. p 112 

 b Leaves opposite in pairs, the floating ones ovate 



C 'alii trie he. p 1 80 



157 a Flowers irregular, blue, with a tubular perianth 



Pontederia. p 132 

 b Flowers regular, perianth not completely as in a 158 



158 a Leaves arrow-shaped, with spreading lobes 159 



b Leaves not arrow-shaped 160 



159 a Flowers white, arranged in whorls on the stem 



Sagittaria. p 1 12 

 b Flowers greenish, surrounded by a narrow green spathe 



Peltandra. p 131 



36 



