Limnophila is a genus of flowering plants in the plantain family, Plantaginaceae. It is distributed in tropical and subtropical regions of Africa, Asia, Australia, and the Pacific Islands. Species are known commonly as marsh weeds.
These are annual or perennial herbs. They grow in wet habitat, such as marshes, and some are aquatic. Some species are glandular and aromatic. Plants of the genus vary in form, from erect to prostrate, and with branching or unbranched stems. Submerged leaves are whorled; aerial leaves are whorled or oppositely arranged. The leaves are lance-shaped or pinnate, and the blades have smooth or serrated edges. Some species have flowers solitary in the leaf axils, and others have flowers in inflorescence. The sepals are arranged in a tubular calyx, and the corolla is tubular or funnel-shaped. The corolla has a lower lip with three lobes and an upper lip that is unlobed or double-lobed.
Cabomba caroliniana, a plant in a different family, is noted for having leaves that resemble those of Limnophila.