There are three varieties of Wrightia Religiosa: the most common one has a cluster of small drooping single white flowers and there is a less common double flowered form. There is also a variety with extremely small leaves known as Vietnam Wrightia (越南水梅）which is less commonly seen. The smaller leaf varieties are more difficult to grow.
Shui Mei grow quickly in our topical country. You have to prune the plants heavily every few months to prevent them growing out of the shade. Defoliation not only will reduce leaf size and also will produce more flowers. I always pinch away all leaves every 2 months, and flowers will develop in 3-4 weeks time after that, I will get lovely white blooms, fill the place with a very sweet fragrance. Repotting is a must too, should be done at least every two years.
Shui Mei plant will occasionally get scale, mealy bug, or aphids but it is easily controlled with pesticide spray.