Spergularia

1. Sepals at least 4 mm long (usually 5); seed with a thin wing ca. 0.3 mm broad.

S. media

1. Sepals mostly not over 4 mm (usually 2–3.5); seed usually wingless.

2. Stamens 1–3 (rarely more); plant of saline habitats.

S. marina

2. Stamens usually 10 (or some aborted); plant of non-saline habitats.

S. rubra

All species found in Spergularia

Spergularia marinaSALT SPURREY 
Spergularia mediaSALT SPURREY 
Spergularia rubraSAND SPURREY 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. March 27, 2017. http://michiganflora.net/genus.aspx?id=Spergularia.