Triglochin

1. Carpels and stigmas 6; groups of mature fruits broadly rounded at base, about 1 (–3) times as long as broad (or even shorter), the central axis not winged.

T. maritima

1. Carpels and stigmas 3; groups of mature fruits narrowly tapered to base (the individual follicles very sharp-pointed basally), about 5–7 times as long as broad. the central axis winged.

T. palustris

All species found in Triglochin

Triglochin maritimaCOMMON BOG ARROW-GRASS 
Triglochin palustrisSLENDER BOG ARROW-GRASS 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 15, 2017. http://michiganflora.net/genus.aspx?id=Triglochin.