Luzula

1. Flowers grouped in small heads or short dense spikes; capsule usually no longer than the perianth.

2. Flowers 3-6 in small heads; inflorescence much branched; tepals whitish; plants colonial from short-creeping rhizomes.

L. luzuloides

2. Flowers mostly 5-12 in short dense spikes; inflorescence umbel-like, sparsely branched; tepals pale to dark brown (at least at maturity); plants ± cespitose, without evident rhizomes.

3. Seeds 1.1–1.6 mm long, with caruncle ca. 0.4–0.6 mm long.

L. multiflora

3. Seeds 0.7–1 mm long, with caruncle 0.2–0.3 mm long.

L. pallidula

1. Flowers solitary at ends of branches of the inflorescence; capsule at maturity at least slightly longer than perianth.

4. Inflorescence umbelliform, the bases of the primary branches close together; branches unforked or at most with 1 or 2 flowers in addition to terminal one; mature perianth 2.5–4 mm long; outer end of seed with conspicuous appendage, which may be almost as long as the body of the seed.

L. acuminata

4. Inflorescence cymose, the primary branches arising from bases distinctly spaced along a short axis; branches forked at least once or twice; mature perianth 2–2.5 mm long; seeds without appendage.

L. parviflora

All species found in Luzula

Luzula acuminataHAIRY WOOD RUSH 
Luzula luzuloidesWHITE WOOD RUSH 
Luzula multifloraCOMMON WOOD RUSH 
Luzula pallidulaEURASIAN WOODRUSH 
Luzula parvifloraSMALL-FLOWERED WOOD RUSH 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 17, 2017. http://michiganflora.net/genus.aspx?id=Luzula.