Pontederiaceae

1. Flowers yellow, regular, solitary; leaves less than 1 cm broad, borne along leafy stem, usually submersed.

Heteranthera

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.

Pontederia

2. Plants free-floating, petioles modified into bulbous, inflated "floats.

Eichhornia

All species found in Pontederiaceae

Eichhornia crassipesWATER-HYACINTH 
Heteranthera dubiaWATER STAR-GRASS 
Pontederia cordataPICKEREL-WEED 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 16, 2018. https://michiganflora.net/family.aspx?id=Pontederiaceae.