Rostellularia procumbens, commonly known as water willow (Marathi: करंबल, romanized: Karambal, पित्तपापडा, Pitpapada, कलमाशी, Kalmashi,[2]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.

[1] It is found in higher elevations, commonly in humid areas.

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

Pink flowers are born in terminal cylindrical spikes.