It grows up to 1 m tall. The flowers are two-lobed, the long axis up to 5 cm long; they are magenta to reddish-violet.
An extract of its leaves is used as a food colouring, and imparts a magenta tone to some Vietnamese foods, particularly in glutinous rice dishes such as xôi lá cẩm, a sweet dessert.
The plant is used in traditional Chinese medicine. The leaves have been used in water extract decoctions for the treatment of ailments including cough, dysentery, diarrhoea and bronchitis.
(The plant was earlier known as Peristrophe bivalvis)
Reference
Plants of Singapore