1. Flowers yellow, regular, solitary; leaves less than 1 cm broad, borne along leafy stem, usually submersed.
1. Flowers blue-violet, borne in a dense inflorescence; leaves (except for one large bract in Pontederia) arising near base of plant, mostly emersed and over 1 cm broad.
2. Plants rooted in soil; petioles not inflated and bulbous.
2. Plants free-floating, petioles modified into bulbous, inflated "floats.
All species found in Pontederiaceae
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. May 26, 2017. http://michiganflora.net/family.aspx?id=PONTEDERIACEAE.