Streptanthus longisiliquus (orth. var. S. longisiliqus) is a species of flowering plant in the mustard family known by the common name long-fruit jewelflower. It was first described to science in 2007. It is endemic to northern California, where it is known from Butte, Tehama, and Shasta Counties. It can be found in forest and woodland habitat in mountains and foothills. It is a short-lived perennial herb producing a few-branched stem up to 1.2 to 1.5 meters in maximum height. It is mostly hairless except for some light hairs on the inflorescences and sometimes the leaf petioles. The basal leaves have oval or spoon-shaped blades up to 10 centimeters long, usually with smooth edges. Leaves higher on the stem are oval or oblong and lack petioles, their bases often clasping the stem. Flowers