At some point in our lives, we would experience the joy appreciating the beauty of flowers, the happiness in giving flowers or and the excitement of receiving them. A flower itself does not have any meaning, just like a cat or a fish. But it's the human emotion that gives a certain value to it and our interpretation gives it a consistent meaning over time. For example, you will see a man giving a bunch of red roses to express his admiration and love to a woman. But you will hardly see anyone with the same bunch of red roses at a funeral. The meanings of the same flower would evoke different emotions with different implications on a different context.
It is the same with flower tattoos. Different flower tattoos would evoke a different emotion and therefore a different meaning to the beholder. Not only the women are getting flower tattoos, some men like to ink them too. Most flowers have acquired a consistent meaning over time, but when you combine it with a different object in a tattoo, the meanings get altered altogether. Have you seen a black rose with a chain around it as a tattoo on a man's chest? Do you think the flower tattoo would mean love or perhaps hatred?
The fact is that flower tattoo designs are going to be popular. Dragons are popular with men but flowers are most sought after by women. Maybe it's the color, or the shape, or the scent of it or a combination of all the senses that makes people want to see, touch and smell it. Flowers can calm a person and gives you a sense of peace. Having a flower tattoo inked on your body is like having a permanent flower with you all the time, except this particular flower does not withered over time.
