Context: Flower evolution continues to the present day; modern flowers have been so profoundly influenced by humans that some of them cannot be pollinated in nature. Many modern domesticated flower species were formerly simple weeds, which sprouted only when the ground was disturbed. Some of them tended to grow with human crops, perhaps already having symbiotic companion plant relationships with them, and the prettiest did not get plucked because of their beauty, developing a dependence upon and special adaptation to human affection.

Question: How long has flower evolution occurred? 
Answer: present day

Question: Humans have effected some flowers so much they can no longer do what in nature?
Answer: pollinated

Question: What heritage do many modern domesticated flower species have?
Answer: formerly simple weeds

Question: Why did weeds grow with human crops?
Answer: symbiotic companion plant relationships

Question: What feature helped flowers not get plucked?
Answer: prettiest

Question: What has happened to weeds due to human influence?
Answer: Unanswerable

Question: How long has weed evolution occurred?
Answer: Unanswerable

Question: What was the origin of many simple weeds?
Answer: Unanswerable

Question: What have weeds developed a dependence on?
Answer: Unanswerable

Question: What characteristic caused crops not to be harvested?
Answer: Unanswerable