st john's wort: any of numerous plants of the genus Hypericum having yellow flowers and transparently dotted leaves; traditionally gathered on St John's eve to ward off evil
plant: (botany) a living organism lacking the power of locomotion
xeroderma pigmentosum: a rare genetic condition characterized by an eruption of exposed skin occurring in childhood and photosensitivity with severe sunburn; inherited as a recessive autosomal trait in which DNA repair processes are defective so they are more likely to chromosome breaks and cancers when exposed to ultraviolet light