blessed thistle

definition: annual of Mediterranean to Portugal having hairy stems and minutely spiny-toothed leaves and large heads of yellow flowers
example:
speech part: noun
synonyms: sweet sultan
definition: tall Old World biennial thistle with large clasping white-blotched leaves and purple flower heads
example:
speech part: noun
synonyms: milk thistle lady's thistle holy thistle

How blessed thistle is being used?