Eryngium spinosepalum is an uncommon species of flowering plant in the carrot family known by the common name spinysepal eryngo, or spiny-sepaled button celery. It is endemic to California, where it is known from the eastern Central Valley and adjacent Sierra Nevada foothills. It is a plant of vernal pools and similar wet habitat in the hills and grasslands. This is an erect perennial herb growing up to about 75 centimeters tall with a thick, hairless branching stem. The leaves are widely lance-shaped to oblong, edged with sharp, pointed lobes, and up to 35 centimeters in length. The inflorescence is an array of spherical flower heads each up to 2 centimeters wide and surrounded by several narrow, pointed bracts which may be edged in spines. The heads bloom in white petals.