Eriogonum siskiyouense is a rare species of wild buckwheat known by the common name Siskiyou buckwheat. It is endemic to the southern Klamath Mountains of far northern California, where it is known only from the area between Mount Eddy and the Scott Mountains around the border between Siskiyou and Trinity Counties. It is a member of the local serpentine soils flora. This perennial herb forms mats up to half a meter wide around a woody caudex. It bears clusters of small rounded to oval leaves each under a centimeter long and coated in gray woolly fibers at least on the undersides. The flowering stem arising from the caudex has a whorl of two to four leaflike leafs around the middle and is otherwise naked but for a coat of woolly hairs. Atop the scape are the bright yellow flowers, which are usually arranged in a spherical cluster.