This is green star sedge, Carex viridistellata. Goose Creek is an excellent place to see this rarity. It was first described as a separate species in 2013 after its genome was analyzed. Green star has only been found in a limited area of southeast Michigan and adjacent Ohio and Indiana. It presents very much like C. cryptolepis, but was discovered to be genetically distinct. Plants that seem to disguise themselves as their relatives are called cryptic species. These plants are plentiful at Goose Creek, and now have conspicuous spiked fruiting heads. Here we see it late in the flowering stage with a spent staminate spikelet at the top, and white-fringed pistillate spikes that appear to be still active.