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.
2.1 Genomic Imprinting. For some genes, only one copy is expressed. Expression of these genes is variable depending on which parent the gene came from, a process known as genomic imprinting.In this way, the active gene is preferentially transmitted from one parent over the other.he methylation prevents that gene from being expressed. Genomic imprinting is a reversible form of gene inactivation and is not considered a mutation. For instance, Jane inherits two copies of a paternally imprinted gene.