Trichophorum

1. Culms terete or several-ridged, smooth; anthers 1.1–2.5 mm long (not including a short prolonged tip); body of achenes 1.5–1.7 mm long.

T. cespitosum

1. Culms 3-angled, scabrous; anthers 0.6–1.1 mm long; achenes various.

2. Perianth bristles ciliate, slightly or not at all exceeding the blunt achene; scales of spikelet not more than 7; achenes ca. 1.6–1.8 mm long.

T. clintonii

2. Perianth bristles smooth, several times as long as the apiculate achene at maturity; scales of spikelets slightly more than 7; body of achene less than 1.5 mm long.

T. alpinum

All species found in Trichophorum

Trichophorum alpinumBULRUSH 
Trichophorum cespitosumBULRUSH 
Trichophorum clintoniiCLINTON'S BULRUSH 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. October 18, 2017. http://michiganflora.net/genus.aspx?id=Trichophorum.