This picture is showing a flower of Choi Sum. It is monoecious. The flowers arranged in a raceme and born on the tip of the branchlet. It contains 4 free sepals and 4 free yellowish petals. The stamens are tetradynamous which include 4 longer and 2 shorter. The ovary is superior and parietal. It only contains one locule, divides with a false septum.

Moreover, Chio Sum is a popular host plant for butterflies such as the Cabbage white which is a common whitish butterfly. Therefore, pesticides are commonly used when cultivating Chio Sum. This results in an armor race between farmers and butterflies. Pesticides resistance are more frequently developed among insects.

I am curious about whatever is there any wild Chio Sum population? Is the cultivated Chio Sum different from the wild population due to selective pressure like roses? Will their gene sequence differ significantly? What are the selected traits?

from the picture, we can see that the whorl arrangement:
there are two sepals and four petals, the sepal grow along one of the said of symmetry, there are six stamens which have the same location as the sepal and petal, there is one single pistil.

regarding the relationship of choy sum with other plants, they actually are one of the subspecies of 油菜Nanohana.

I would like to know about whether the flower of choy sum has any adaption to attract the pollinators except its bright colour? (like special ordour/ UV marker)