Juncus patens 'Carman's Grey'

'Carman's Gray' _ 'Carman's Gray' is a clump-forming, rhizomatous, evergreen perennial with erect, leafless, grooved, blue-grey to blue-green stems and small clusters of brown flowers from spring into autumn.

https://www.shootgardening.co.uk/plant/juncus-patens-carmans-gray

Juncus 'Carman's Grey', a selection of the California native Juncus patens, is one of our favorite rushes (no relation to R. Limbaugh). Introduced and named by grass guru, John Greenlee, Juncus 'Carman's Grey' was named for former California Nurseryman, Ed Carman. No leaves, just evergreen slender, upright steel blue stems to 22"...not leaning either to the right or left. The winter interest and color combinations possibilities of this architectural 2' wide specimen are endless! We grow this wonderful clumper in regular garden soil, or in a bog, or in an aquatic garden...incredibly versatile!

https://www.plantdelights.com/collections/plants-that-start-with-j/products/juncus-patens-carmans-grey