1. Home
  2. >
  3. Hong Kong's Wild Stars

The Mighty Wildflower – Chinese Rain Bell (Strobilanthes cusia)

Dec 2018
Author : Green Power

Although Chinese Rain Bell is a tiny wildflower, its small, bell-shaped flowers are unique; with a touch of light purple, these small flowers are elegant and adorable! It not only has appearance that is pleasing to the eye but its rhizomes and roots also have medicinal value. They are both beautiful and useful!

Chinese Rain Bell is a perennial Acanthaceae plant. It grows in the woods, valleys or damp stream sides. Its leaves have opposite arrangements, and are oval with saw-toothed edges. The flowers look like miniature bells. When in bloom, the tiny purplish flowers are particularly eye-catching among the green shrub. The Acanthaceae family also include Strobilanthes tetraspermu, Strobilanthes dimorphotricha, etc. Their flowers appear to be very similar to each other.

Before synthetic dyes became popular, people used natural materials, such as plants, to develop dyes. Chinese Rain Bell used to be one of them. Due to its strong adaptability, speedy growth and being readily cultivated, it was widely used in the past as a natural dye. Its stem and leaves are rich in indigotin. Through the complicated processes of soaking, fermentation, precipitation, water filtration, etc., this can be refined into indigo dye. Since indigo is “trichromatic”, it can be recombined into countless colours when mixed with other dyes, if the quantities are carefully controlled. For example, Cape Jasmine is a bright yellow dye, which was often used in ancient times; when it is combined with Chinese Rain Bell, the dye can turn fabric emerald green.


Chinese Rain Bell has medicinal value. Its rhizomes and roots can be refined into an herb called “Nan Ban Len Gen”, which can “clear heat-toxicity, cool blood and subside swell”. In addition to its affordable price, it is very useful. However, please do not confuse it with “Ban Lan Gen” because their functions are not exactly the same and they cannot replace each other. “Ban Lan Gen” is from Isatis indigotica and belongs to the Brassicaceae family. It grows in North and Central China.

Chinese Rain Bell is not only useful to humans, it is also a primary food for Orange Oakleaf (Kallima inachus). Like other butterfly caterpillars, the Orange Oakleaf catterpillars are also picky eaters. Their primary food is Acanthaceae and they particularly like Chinese Rain Bell. The Orange Oakleaf mothers will only lay eggs on Acanthaceae, so that their babies will have enough food after they are born.

Orange Oakleaf is known for “posing”. As revealed in its Chinese name, the adults look exactly like dead leaves, which allows them to easily hide from predators. As they hide in the jungle by posing as dead leaves, they are very hard to find. In addition, it is a rare species in Hong Kong. If you would like to get a glimpse of it, you might wait near Chinese Rain Bell and observe carefully!

© Peggy Chung
© Peggy Chung
As shown in the photo, Chinese Rain Bell and Strobilanthes tetraspermu look very alike.
The Orange Oatleaf looks exactly like a leaf.

Subscribe to Green Power's latest news

Contact Us

3961 0200 (T)
2314 2661 (F)
Rm. 2314, 23/F.,Gala Place,
56 Dundas Street, Mongkok, Kln.
Opening Hours:
Monday to Friday 9:30 a.m.-1:00 p.m.;
2:00 p.m.-6:00 p.m. (Closed on Saturday, Sunday and public holidays)