Kanavazhai (Commelina benghalensis)

Kanavazhai, kankawa in Hindi, is Benghal dayflower, a creeping weed of the monsoon with small blue flowers that open in the morning and wilt by midday. It is common in gardens, field edges and crops across India. Unusually, it also makes hidden flowers on underground stems that set seed without opening, which helps it survive weeding. It has become a serious weed of cotton in the United States.

Botanical name: Commelina benghalensis L.
Family: Commelinaceae
Tamil: Kanavazhai
Hindi: Kankawa
Parts used: Leaf
Habit: Blue dayflower, a creeping monsoon weed
Last updated: 2026-10-27

How to recognise Kanavazhai

It is a creeping, branching herb that roots at the nodes, with fleshy, jointed stems.

The leaves are oval, with a sheath around the stem that has a fringe of reddish hairs at its mouth.

Each flower has two large, rounded blue petals above and one tiny pale petal below.

The flowers emerge from a folded, funnel-shaped green bract, called a spathe, at the stem tips.

Some stems grow underground and bear small, closed flowers that self-pollinate.

Traditional use of Kanavazhai

Kitchen

Young shoots are cooked as a leafy vegetable in parts of Africa and South Asia.

African and South Asian food practice

Farming

The juicy stems are cut as fodder for cattle and pigs in some villages.

Indian farm practice

Modern notes on Kanavazhai

Underground flowers give it a reserve of seed that survives surface weeding and herbicides.

It tolerates glyphosate better than many weeds, which made it a major problem in herbicide-tolerant cotton in the southern United States.

Leaf extracts have been studied in laboratories, but there are no reliable human trials.

Kanavazhai safety

If eaten, cook the young shoots and eat them in normal vegetable amounts. Pick only from clean ground away from roads and sprayed fields.

Ecology and sourcing

It is native to tropical Asia and Africa.

Bees and hoverflies visit the morning flowers for pollen.

Stem pieces root easily, so it regrows from fragments left after weeding.

Related plants

Questions about Kanavazhai

Why is Kanavazhai called dayflower?

Each flower lasts only a single morning.

Is Kanavazhai related to the banana?

No. The Tamil name only sounds similar.

Why is Kanavazhai hard to weed out?

Stem pieces reroot and underground flowers keep seeding.

Is Kanavazhai edible?

Young shoots are cooked in some regions.

How do I recognise Kanavazhai?

Two big blue petals above one tiny one.

Sources

Educational page about a plant. It is not medical advice, not a diagnosis, and not an offer to sell. Traditional use is historical. If you need care, ask a licensed clinician. Questions: hello@meevamed.com.