I know, Gentlemen and Plants? Why are they even related? Well, as funny as it sounds, this is not a unique cultural phenomena of China. In the west, rose represents love, in China, waterlily/lotus represents a person with great integrity. We humans are always trying to project our values onto things in our surroundings.
There are four plants in China that always show up as a package: they represent the ideal morals and values a true gentlemen should possess. They are in daily speeches, writings, paintings and many other things. They are 梅 (mei)、兰(lan)、竹(zhu)、菊(ju); plum, orchid, bamboo and chrysanthemum.
Plum, or rather, plum trees' flowers, are the first one we encounter in this pack of four plants. Plum flowers are traditionally treated as an embodiment of a person's strength and perseverance. Plum flowers blossom in late winter early spring, often while snow is still falling. The flowers bloom despite the harsh environmental conditions, thus are often used as a metaphor for someone's ability and integrity to face hardship with courage. There's no shortage of the representations of plum flowers on China's TV screen.
The interesting thing about orchid is that the most valuable and rare flowers grow in remote mountains. This quality of orchid is a great natural representation of a very commonly praised and admired quality of a scholar...being a recluse and stay away from the messy politics of the establishment. Besides, orchid has lovely scents, and it often takes years for a rare plant to bloom, which can also be interpreted as a scholar's patience and steadfast character. You see this flower in many Chinese and Korean dramas, often as a pet plant of highly educated people. The character 兰，is a very common given name for girls in ancient China. It is still being used today as a girl's name although much less so.
Bamboo is unique among the four gentlemen plants. While the others are appreciated for their flowers (and their embodied characters), bamboo is loved because of its strong yet flexible body. Bamboos are straight, representing the straight characters of a gentleman; bamboos are hollow in the middle, representing tolerance and generosity. The plant can stay dormant for years before suddenly grow out of the soil and turn into a proper tree in days, representing patience and capability. Of course, being extremely strong yet flexible is also a great quality that you can easily relate to human characters. Bamboo is often used to represent men, although it's not uncommon to use for women.
Chrysanthemum usually blooms in autumn, after all the other flowers have withered. This particular character become literary scholar's favourite, as it represents the quality similar to orchid – being aways from the hustle and bustle and competition. Chinese scholars have this obsession with being singled out, being considered a loner and have one's own merit that is independent of the society's opinion. Plus the flower usually carries a very clear and cool scent, fitting into this kind of value system perfectly.
These four plants are heavily used in all aspects of Chinese culture. Understanding the reasons why can help you get some insight into the traditional values of the Chinese society. Of course the love for these plants is deeply rooted in the Confucius value and morality system, which dominated China's philosophy and social practices for centuries. These days, even though everyone understands what these four plants represent, they are no longer so heavily referenced or used in paintings, poetry and other cultural "products", as the Confucius morality is gradually fading into the past, so is the fixation on these plants. People are free to love whatever flowers they love, and appreciate them for what they are – just flowers – without the need to give their preferences any moral justification.