Justicia (syn. Acelica, Adhatoda, Amphiscopia, Anisostachya, Aulojusticia, Averia, Beloperone, Calliaspidia, Calymmostachya, Chaetothylopsis, Chiloglossa, Cyphisia, Cyrtanthera, Cyrtantherella, Dianthera, Dimanisa, Drejerella, Duvernoia, Emularia, Ethesia, Glosarithys, Harnieria, Heinzelia, Hemichoriste, Heteraspidia, Ixtlania, Jacobinia, Kuestera, Libonia, Lophothecium, Lustrinia, Nicoteba, Orthotactus, Parajusticia, Petalanthera, Plagiacanthus, Plegmatolemma, Porphyrocoma, Psacadocalymma, Rhacodiscus, Rhiphidosperma, Rhyticalymma, Rodatia, Rostellaria, Rostellularia, Saglorithys, Salviacanthus, Sarotheca, Sericographis, Simonisia, Solenochasma, Stethoma, Tabascina, Thalestris, Thamnojusticia, Tyloglossa in Plant Systematics) is a genus of about 420 species of flowering plants in the family Acanthaceae, native to tropical to warm temperate regions of the Americas, with two species occurring north into cooler temperate regions. Common names include water-willow and shrimp plant, the latter from the inflorescences, which resemble a shrimp in some species.