Fimbristylis puberula var. interior (Britton) Kral
Family: Cyperaceae
chestnut sedge,  more...
[Fimbristylis interior Britton]
Fimbristylis puberula var. interior image
from USDA Plants website  
Etymology: Fimbristylis: fimbria for "fringe" and stylus for "style," which is fringed with hairs in genuine species
Plants: perennial sedge; stems base of culm (grass stem) swollen, knotty, closely joined
Conservation Status: Endangered