It is a submerged plant with slender, branching stems about 20–70 cm (8–28 in) long. The light green, narrow leaves are up to 6 cm (2 in) long and 1-2mm wide, slightly broadening at the tip. The leaves which can float on top of the water, are shorter and wider, they are also light brownish or pinkish green. It has tiny inconspicuous green flowers and fruits, and has a flowering period of between May to October. or between April to September in the UK.
It is widespread and fairly frequent in Britain, particularly in south eastern England.
It is found in rapidly flowing streams, which are well oxygenated, and freshwaters, from sea level to about 1,200 m (3,900 ft) above sea level. This plant can grow in shallow waters and can also adapt to a deeper water level, especially after flooding. It can also be found in or near ponds, ditches, in still or slow moving water.
- "Callitriche hamulata Kütz. ex W.D.J.Koch is an accepted name". theplantlist.org (The Plant List). 23 March 2012. Retrieved 21 April 2020.
- "Callitriche hamulata Kütz. ex W.D.J.Koch | Plants of the World Online | Kew Science". Plants of the World Online. Retrieved 1 February 2021.
- W. Vivian De Thabrew A Manual of Water Plants, p. 43, at Google Books
- "Intermediate Water-starwort". Retrieved 27 December 2016.
- "Callitriche hamulata Kütz. ex W.D.J. Koch". Retrieved 27 December 2016.
- "Callitriche hamulata | International Plant Names Index". www.ipni.org. Retrieved 11 April 2021.
- Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 420.
- Jon Feilberg A Phytogeographical Study of South Greenland Vascular Plants (Bioscience 15, 1984), p. 13, at Google Books
- S. M. Haslam and P. A. Wolseley River Vegetation, Its identification, assessment and management, p. 46, at Google Books