Xyris

1. Plants bulbous (swollen) and hard at the base; keel of lateral sepals ± pubescent or ciliate from apex to below the middle, with small tuft of longer hairs at apex.

X. torta

1. Plants not swollen but ± flattened and soft at the base; keel of lateral sepals with pubescence absent or limited to terminal half, with or without terminal tuft.

2. Flowering bracts with prominent central green patch 2–3 mm long (at least the larger ones); keels of lateral sepals fringed or lacerate on terminal half, often with small tufts of hairs at apex; sides of lateral sepals becoming very pale yellow-brown or whitish, ± transparent, very thin, and membranous toward edges; largest leaves usually 2–4 mm wide; widest portions of scapes sometimes over 1 mm in diameter; seeds very plump-ellipsoid, ca. (0.4–) 0.5 (–0.6) mm long, with very obscure longitudinal lines.

X. difformis

2. Flowering bracts (not necessarily the sterile lower bracts) with central green or grayish patch absent or at most 2 mm long; keels of lateral sepals entire or slightly toothed toward the tip (which usually bears 2 tiny teeth but no tuft of hairs); sides of lateral sepals rather uniform opaque or translucent brownish to their edges, firm; leaves all less than 2 mm wide; scape never over 1 mm in diameter; seeds ellipsoid, ca. 0.7–0.8 mm long, with distinctly contrasting darker longitudinal lines.

X. montana

All species found in Xyris

Xyris difformisYELLOW-EYED-GRASS 
Xyris montanaYELLOW-EYED-GRASS 
Xyris tortaYELLOW-EYED-GRASS 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. November 22, 2017. http://michiganflora.net/genus.aspx?id=Xyris.