Hornwort (Ceratophyllum demersum): grower data and range
A rootless stem plant that Tropica rates easy with low light and CO2 demand, growing stems up to 80 cm [1]. The World Checklist of Vascular Plants records it as native to 235 regions on every inhabited continent [4].
Grower data
As published by Tropica Aquarium Plants[1]
- Light demand
- LowTropica: medium light demand is 0.5 W/L.
- CO2 demand
- LowTropica: medium need 6–14 mg/L; high approx. 15–25 mg/L.
- Growth rate
- Not published by the source
- Difficulty
- Easy
| Type | Stem |
|---|---|
| Origin (grower) | Cosmopolitan |
| Height after two months | 5 - 30+ cm |
| Placement | midground, background, floating[2] |
| 'Foxtail' form: growth (second grower) | Very fast[2] |
| 'Foxtail' form: light (second grower) | Medium[2] |
| Care height (second grower) | 15–40 cm[2] |
| Water hardness (maximum) | Hard[2] |
Name and range
- Accepted name
- Ceratophyllum demersum L.[4]
- Family
- Ceratophyllaceae
- Native range
- Alabama, Alaska, Albania, Alberta, Algeria, Altay, Amur, Angola, Argentina Northeast, Argentina Northwest, Argentina South, Arizona, Arkansas, Assam and 221 more regions
- Introduced in
- Cape Provinces, Hawaii, Mauritius, New Zealand North
- Records
- WCVP via GBIF and POWO
What the grower data says
Tropica rates hornwort easy, with low light and CO2 demand; its growth-rate field is blank, so that rating is not published [1]. Aquasabi profiles a form sold as ‘Foxtail’ and rates it easy and “very fast”, with medium light, no need for added CO2, a care height of 15–40 cm and water up to “hard” [2].
Tropica’s plant came from the wild: it was found in a small tributary in Bolivia during an expedition to the Rio Guaporé, the river on the Brazil–Bolivia border [1]. Tropica says this form is distinguished by leaves set closer together and by side shoots, which give it a compact look, and that it is hardier, with stalks that do not break as easily as those of other Ceratophyllum forms [1]. Stems can reach 80 cm tall and 5 cm wide [1].
A plant without roots
Hornwort has no roots as such, Tropica notes, yet it can still be planted in the bottom of an aquarium [1]. Aquasabi lists it for three positions: middle ground, background and the water surface, and as a spawning plant [2]. Weighted into the substrate it behaves like a stem plant; left loose, it floats.
Rootless plants take everything from the water. Tropica’s fertilizer guide notes that liquid fertilizer is the only way to feed plants whose roots are not in the substrate, such as floating plants [3]. Root tabs do nothing for hornwort.
Names and range
Ceratophyllum demersum L. was named by Linnaeus in 1753 and is accepted in the World Checklist of Vascular Plants, in its own family, Ceratophyllaceae; WCVP lists a single synonym, Dichotophyllum demersum (L.) Moench [4]. Tropica’s origin field says “Cosmopolitan” [1], and the checklist bears that out: it records the species as native to 235 regions, from Alaska and Alberta to Argentina, across Europe, Africa and Asia [4, 5]. It lists only four regions where it is introduced: the Cape Provinces of South Africa, Hawaii, Mauritius and New Zealand’s North Island [4].
Being native almost everywhere does not make dumping it harmless: in places where it is introduced, such as those four, it is an alien plant. Dispose of surplus hornwort away from water; see invasive aquarium plants and safe disposal.
Questions
Does hornwort have roots?
No. Tropica says Ceratophyllum has no roots as such, but it can still be planted in the bottom of an aquarium [1].
Can hornwort float?
Yes. Aquasabi lists it for the water surface as well as the middle ground and background [2].
Similar plants
Related guides
- FertilizersNitrogen, phosphorus and potassium in planted tanksWhat N, P and K do in plants, the forms plants take up, how aquarium dosing expresses them, and what growers and dosing methods say about each.
- Algae & problemsGreen water: why aquarium water turns green and how it clearsGreen water is a bloom of free-floating microscopic algae. What causes it, what Tropica and Aquasabi recommend, and how UV, blackouts and water changes compare.
- Algae & problemsInvasive aquarium plants and how to dispose of trimmings safelySeveral common aquarium plants are established in US waters and two are federal noxious weeds. What the official records say, and how to dispose of trimmings safely.
Compare it with the other profiled plants in the plant parameter table.
Sources
- Ceratophyllum demersum (plant details, 021APOR). Tropica Aquarium Plants. Type, origin, height, light, CO2 and difficulty; growth blank; description: collected in a tributary of the Rio Guaporé in Bolivia, no true roots but can be planted, stems up to 80 cm and 5 cm wide, dense leaves and side shoots, sturdier stems than other forms. Accessed October 12, 2026.
- Ceratophyllum demersum 'Foxtail' (Aquarium Plant Profile). Aquasabi. Placement: middle ground, background, spawning plant, water surface; easy; very fast; medium light; hardness up to hard; 15–40 cm; CO2 not required. Accessed October 12, 2026.
- Fertiliser and CO2. Tropica Aquarium Plants. Liquid fertilizer is the only way to feed plants whose roots are not in the substrate. Accessed October 12, 2026.
- Ceratophyllum demersum L.: World Checklist of Vascular Plants record (via GBIF). Royal Botanic Gardens, Kew; dataset published 2026-06-04, CC BY 4.0. Accepted name, family, synonyms, native and introduced range. Accessed October 12, 2026.
- Ceratophyllum demersum: Plants of the World Online. Royal Botanic Gardens, Kew. Addressed by IPNI identifier 30006047-2; POWO displays the same WCVP data. Accessed October 12, 2026.