Peristrophe roxburghiana is one plant that most older generation Singaporeans would be familiar with. It is a flowering plant that belongs to the Acanthaceae family and is native to southeastern Asia, southern China, and South East Asia. It thrives in the humid lowlands and grows as a lush, herbaceous perennial shrub, up to a height of 0.6 m tall, with lanceoate- to ovoid-acute-shaped leaves.
Unlike many of its more showy ornamental relatives, the true flowers of Peristrophe roxburghiana are not magnificient and they emerge from a small, terminal flower spike. Each flower consists of only two petals which are coloured pink which may appear magenta to reddish-violet to others. There are reports that state there are plants with white flowers.
Despite of the lack of beauty in its blooms, Peristrophe roxburghiana is a plant that is valued as a source of natural food dye. An extract of its leaves imparts a magenta colouring which is used to colour various food desserts in Vietnamese cuisine. The Chinese here knows it via the name ‘红丝线’ (hong si xian) which translates into ‘red silk threads’, with reference to the magenta/reddish dye that is found in its leaves which can be extracted by boiling leaves in water. The leaves of Peristrophe roxburghiana have a sweet taste with cooling properties and are also used medicinally to treat cough, dysentery, diarrhoea and bronchitis. Pregnant women should refrain from consuming this plant.
Peristrophe roxburghiana has a place in any tropical medicinal herb garden. Grow it in a sunny to semi-shaded and well-drained spot with moist, fertile soil. Prune this plant to shape periodically to keep growth in check and ensure a neat and tidy appearance. It propagates easily from stem-cuttings and sections of internodal stem-cuttings and tip-cuttings root easily without any rooting hormone powder. It is relatively pest- and disease-free.
