Whether or not the story is true, the symbolism of the thistle (ahem, sorry for the pun) took root and is honored to this day. Other facts about the thistle include that it is a biennial plant, meaning it takes two years to complete its life cycle. It reseeds easily. It's a combination of beauty and ruggedness. It has a spreading, invasive root system, hence its classification as weed.
imprinted gene, a gene whose expression has been affected by genomic imprinting so that only a single allele functions, the other being turned off by epigenetic mechanisms during embryonic development.
At the time that the organism produces its own gametes, the imprinted genes are un-methylated. Nonetheless, genomic imprints would be re-instituted in its genome. The location of gene methylation would depend on the sex of that organism. The new gene imprints would consequently affect the phenotype of the its progeny.