This section is from the book "Harper's Guide To Wild Flowers", by Caroline A. Creevey. Also available from Amazon: Harper's Guide To Wild Flowers.
The yellow, fragrant flowers of this species differ from most of the others in that the lower lip of the corolla is the larger, helmet-like, the upper being long, narrow, erect. Spur, long, curved downward. Flower-stalk stout, straight, with few or no leaves and few bladders. Leaves, when they do occur, entire. Scape reaches the top of the water for flowering, 3 to 14 inches high, rooted in bogs or the muddy shores of ponds. May to September.
Newfoundland to Ontario and Minnesota, south to Florida and Texas. There are one or two purple-flowered species which will be noticed.
 
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