Clitoria ternatea, known locally as Nil Katarolu (නිල් කටරොළු) in Sinhala, is a perennial twining herb that has been woven into Sri Lankan traditional medicine, cooking, and natural beauty practices for centuries. Recognised by its distinctive vivid blue — occasionally white — flowers, this climbing legume grows readily across the island's lowlands and disturbed forest margins, twisting along fences and hedgerows with quiet persistence. Today it is attracting renewed global attention as both a functional food ingredient and a source of bioactive compounds.
What does Clitoria ternatea look like?
The plant produces slender, terete stems that wind around supports, carrying compound leaves with five to seven sub-leathery leaflets arranged in an imparipinnate pattern. The leaflets are elliptic-oblong with a blunt tip, giving the foliage a tidy, ordered appearance.
Flowers are papilionaceous — shaped like a butterfly in flight — and appear singly or in small clusters from the leaf axils. The most common form is a deep cornflower blue, though white-flowered varieties also exist. After pollination the plant forms flat, almost straight pods, sharply beaked at the tip, each containing six to ten smooth, yellowish-brown seeds.
What are the traditional medicinal uses of Nil Katarolu?
In Sri Lankan Ayurveda and folk medicine, almost every part of the plant has a documented application. Practitioners draw a clear distinction between the properties of the roots, leaves, and seeds.
- Roots: Traditionally regarded as bitter, cooling, and diuretic. Used in formulations addressing eye conditions (ophthalmopathy), respiratory complaints including bronchitis and asthma, inflammatory disorders, and conditions described in classical texts as vitiated pitta. Roots are also credited with intellect-promoting (nootropic) and tonic properties, and appear in preparations for conditions such as hemicrania, strangury, and helminthiasis.
- Leaves: Applied in traditional practice for ear pain (otalgia), liver-related complaints (hepatopathy), and certain skin eruptions.
- Seeds: Recognised as a source of oligosaccharides and several bioactive compounds; historically used as a mild laxative and in formulations for general vitality.
It is worth noting that while these uses are well documented in classical Ayurvedic literature, anyone considering therapeutic use should consult a qualified practitioner. Traditional knowledge and clinical evidence are not always equivalent.
What phytochemicals are found in butterfly pea?
Modern phytochemical research has identified a notably complex profile of compounds across the plant's tissues, which helps explain its longstanding reputation in traditional medicine.
| Plant Part | Key Compounds |
|---|---|
| Blue flowers | Delphinidin-3,5-diglucoside, delphinidin-3-glucoside and its 3-methyl derivative, malvidin-3-glucoside, kaempferol, cyanin chloride — the anthocyanins responsible for the intense blue colour and its pH-sensitive colour change |
| White flowers | Kaempferol (anthocyanins absent) |
| Roots | Taraxerol, taraxerone, stigmast-4-ene-3,6-dione |
| Leaves | Kaempferol glycosides (3-monoglucoside, 3-rutinoside, 3-neohesperidoside, rhamnosyl variants), aparajitin, β-sitosterol |
| Seeds | p-Hydroxycinnamic acid, flavonol-3-glycoside, adenosine, hexacosanol, β-sitosterol, anthoxanthin glucoside, oligosaccharides |
The plant also has a notably high calcium content relative to many common herbs, which has led researchers to explore it as a dietary calcium supplement in the form of herbal infusions.
How is butterfly pea used in Sri Lankan food and drink?
Nil Katarolu has moved well beyond the dispensary and into the kitchen and the tea cup. The dried flowers steep in hot water to produce a vivid indigo-blue infusion that shifts to purple or pink when an acid such as lime juice is added — a natural pH indicator that makes it a popular choice for colour-changing cocktails and mocktails at Sri Lankan hotels and beach bars.
In everyday households, the flowers are increasingly added to string hopper flour, rice dishes, and traditional sweets as a natural colourant, echoing a practice that has long been common in Thai and Malay cuisine. The resulting blue-tinted string hoppers (indi appa) have become something of a novelty in Sri Lankan culinary tourism — a gentle example of how ancient plant knowledge finds new expression in contemporary food culture. For a broader look at Sri Lanka's Ceylon Green Tea tradition, the island's herbal infusion heritage runs deep.
Flower powder is blended into smoothies and wellness drinks, while cold-pressed extracts are appearing in artisan beverages as consumers seek natural alternatives to synthetic food colours.
How is Nil Katarolu used in natural beauty products?
The antioxidant-rich anthocyanins in the flowers have attracted cosmetic formulators. Butterfly pea extracts are now incorporated into shampoos, conditioners, and hair oils marketed for scalp health and hair strengthening — drawing on both the plant's folk reputation and its measurable antioxidant activity. Hydrating shower gels using Nil Katarolu extracts have also entered the Sri Lankan natural beauty market, often positioned alongside other island botanicals.
How is Clitoria ternatea propagated and where does it grow in Sri Lanka?
Propagation is straightforward: seeds sown in well-drained soil germinate readily, and the plant establishes quickly in warm, humid conditions. It tolerates a range of soil types and is found across Sri Lanka's low country wet zone, dry zone margins, and disturbed forest edges — including around destinations such as the Sinharaja Forest Reserve buffer zone. Its ability to fix atmospheric nitrogen also makes it a useful component in agroforestry systems and home gardens.
The plant flowers through much of the year in Sri Lanka's climate, making fresh flower harvests possible across multiple seasons. Commercial cultivation for the export wellness market is growing, with wildcrafted and organically grown varieties both available.
What is the difference between wildcrafted and cultivated butterfly pea?
Wildcrafted Nil Katarolu is harvested from plants growing in their natural habitat without deliberate cultivation. Proponents argue that wild plants may have higher concentrations of secondary metabolites because they are not subject to agricultural interventions. Cultivated varieties, by contrast, allow more consistent quality control, traceability, and higher yields. For herbal teas and food-grade applications, both forms are available through Sri Lankan producers, and the choice typically comes down to personal preference and certification requirements.
