Isatis tinctoria
Karaites "tzitziyot" have blue-violet threads ("tekhelet") in them. In contrast to rabbinic Jews, Karaites believe that the "tekhelet" source can be any dye, except those produced from impure (a definition mostly overlapping "un-kosher") species, such as the molluscs used by Rabbinic Jews. Instead, Karaites propose that the source of the dye was indigo or woad ("Isatis tinctoria"). Karaites also consider synthetic blue or blue-violet to be acceptable for tekhelet. Contrary to some claims, Karaites do not hang "tzitziyot" on their walls.