Hibiscus rosa-sinensis (family Malvaceae), known colloquially as the Chinese hibiscus, is an evergreen flowering shrub native to East Asia. It is also known as China rose and shoe flower. It is widely grown as an ornamental plant throughout the tropics and subtropics. The flowers are large, (generally red in the original varieties), firm, but generally lack any scent. Numerous varieties, cultivars and hybrids are available, with flower colors ranging from white through yellow and orange to scarlet and shades of pink, with both single and double sets of petals. Despite their size and red hues attractive to nectar-feeding birds, they are not visited regularly by hummingbirds when grown in the tropics. In the subtropical and temperate Americas, hummingbirds are attracted to them on a regular basis.
Hibiscus rosa-sinensis is the national flower of Malaysia. The flowers are used to shine shoes in parts of India, as well as for the worship of Devi. Hibiscus flower preparations are also used for hair care. The flowers themselves are edible and used in salads in the Pacific Islands.
Hibiscus rosa-sinensis is one of many plant genera with a genetic characteristic known as polyploidy, in which the number of chromosomes is far greater than the two ("x" and "y") we commonly think of with human genetics. Polyploidy is a condition where the genetic characteristics of the offspring may be quite different from the parent, or even the grandparent plants, essentially allowing possibly random expression of all the characteristics of all the generations that have gone before. Because of this characteristic, "H. rosa-sinensis" has become popular with hobbyists who cross and recross varieties, creating new named varieties and holding competitions to exhibit and judge the many resulting new seedlings and often strikingly unique flowers.
Often these crosses are sterile, but some are fertile, further increasing the complexity of variability and the possibility of a virtually unlimited number of eventual Hibiscus rosa-sinensis varieties. This further attracts the hobbyists, who have created local and international associations, publications, and manuals to further this hobby, which is practiced with these tropical plants worldwide, including indoors in cold climates.
References : Wikipedia
Here is a collection of the hybrids i grow.