Ranunculus trichophyllus, the threadleaf crowfoot, or thread-leaved water-crowfoot, is a plant species in the genus Ranunculus, native to Europe, Asia and North America. It is a herbaceous annual or perennial plant generally found in slow flowing streams, ponds, or lakes. The daisy-like flowers are white with a yellow centre, with five petals.It is similar in form to Ranunculus fluitans (river water-crowfoot), apart from flower petal number, thread-leaved has on 5 petals and shorter leaves, as thread-leaved prefers slower flowing waters. It also has rounded seed heads which become fruits covered with bristles.The segmented leaves and the plants ability to photosynthesis underwater have been studied.