CASTOR-OIL PLANT (Heb. קִיקָיוֹן, kikayon), the kikayon in the shade of which the prophet Jonah sat outside Nineveh after his prophecy concerning that city's destruction had not been fulfilled. He was glad of the shade, "but God prepared a worm" that attacked the plant so that it withered and Jonah was left unprotected against the burning rays of the sun (Jonah 4:6–11). The identification of kikayon with the castor-oil plant is supported by contextual and linguistic evidences as also by the tradition of the Talmud and translators. The castor is the perennial plant Ricinus communis, which grows wild in the Jordan valley, in the coastal plain, and on wadi banks in other regions of Ereẓ Israel. It grows quickly and produces large, shady leaves. The word kikayon is connected with k'k' the Egyptian name of the plant (in Coptic and Greek: kiki) while in Aramaic and Syriac it was known as ẓeluliva which Rabbah bar bar Ḥana identified as the kikayon of Jonah (Shab. 21a). From its seeds a medicinal oil is the kik oil included by the Mishnah among the oils that may not be used for lighting the Sabbath lamp (ibid., 2:1). The kikayon has also been identified with the calabash gourd (Lagenaria vulgaris), an identification first mentioned in the Septuagint and apparently based on the passage that Jonah built himself a booth at the side of which the kikayon came up. The gourd fits in well with this, being a climber that grows quickly and has large leaves. On these two identifications of kikayon, Abraham ibn Ezra, who quotes them in his commentary, makes the observation that "it is not necessary to know which it is," i.e., it was a supernatural phenomenon, for no plant comes up, as the kikayon was said to do, "in a night," and so it cannot be identified with any ordinary plant growing at present.
Loew, Flora, 1 (1928), 608–11; J. Feliks, Olam ha-Ẓome'aḥ ha-Mikra'i (19682), 136–8. add. bibliography: Feliks, Ha-Ẓome'aḥ, 143.