Ciclospermum leptophyllum (also, Cyclospermum l.) is a species of plant in the celery family known by the common names marsh parsley and fir-leafed celery. This is a plant found worldwide at warm temperate to tropical latitudes and is considered a noxious weed in many areas. It is a taprooted branching herb reaching just over half a meter in height at maximum. It has threadlike green leaves a few centimeters long and small umbels of spherical flowers.