Rostellularia procumbens, commonly known as water willow (Marathi: करंबल, romanized: Karambal, पित्तपापडा, Pitpapada, कलमाशी, Kalmashi,Tamil: கோடகசாலை, romanized: Kōṭakacālai), is a small flowering plant belonging to the Acanthaceae family. It is native to the Indian subcontinent, Indochina, China, Peninsular Malaysia, Sumatra, Java, Sulawesi, the Philippines, Japan, and Korea. It is found in higher elevations, commonly in humid areas.

The leaves' juice can be squeezed in the eyes in cases of ophthalmia.

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