Panicled Bulrush (Scirpus microcarpus), also known as Small-fruited Bulrush, can be found along roadsides, streambanks, irrigation ditches, wet meadows, marshes, beaver ponds, springs, foothills, valleys, plains, and mountain sites. It is a perennial grass-like that is easily distinguishable from other grass-likes but can be confused with other bullrush (Scirpus) species. It has a triangular stem, and its leaves can be up to 1/2" wide. Its flowers contain 4 to 6 slender bristles that slightly surpass the achene body but not the scales.
Height: 12" to 40"
Solar Exposure: Part-shade to full-sun
Bloom Color: White to tan
USDA PLANTS Database Link
Pics from https://plants.usda.gov/core/profile?symbol=SCMI2