Thysanocarpus conchuliferus is a rare species of flowering plant in the mustard family known by the common name Santa Cruz Island fringepod. It is endemic to Santa Cruz Island, one of the Channel Islands of California, where has been recently observed at only one location; some years it is totally absent. It is a federally listed endangered species of the United States, and a review by the US Fish & Wildlife Service in 2009 suggests it should remain on the list. The plant's habitat is the coastal scrub on the rocky, windblown slopes and canyons of its single island.