It occurs in seasonally or occasionally permanently inundated water-bodies at 0.5-1 m of usually acid water on organic loam or sometimes sandy substrate, on the margins of marshes, lakes, wet clearings in scrub, often with Baldellia ranunculoides, Hydrocotyle vulgare, Hypericum elodes and occasionally Drosera intermedia, as well as in swards of Eleocharis multicaulis, between stands of Myrica gale (Reduron 2007).

This species needs to be out of the water to flower, like other aquatic Umbelliferae, so the habitat behaves like temporary ponds.

It occurs in the following Habitats Directive habitats (Commission of the European Communities 2009): 

• 2190 Humid dune slacks
• 3110 Oligotrophic waters containing very few minerals of sandy plains (Littorelletalia uniflorae)
• 3170* Mediterranean Temporary Ponds
• 6410 Molinia meadows on calcareous, peaty or clayey-silt-laden soils (Molinion caeruleae)
• 7150 Depressions on peat substrates of the Rhynchosporion

Lansdown, R.V. 2013. Thorella verticillato-inundata. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 15 April 2015.

This plant is endemic to the Iberian Peninsula and the west of France. In Spain, it is only present in Huelva and in Portugal it can be found in Baixo Alentejo, Beira Litoral, Douro Litoral and Estremadura (Castroviejo et al. 2003). The area of occupancy is below 2,000 km² and the populations are severely fragmented.

This species is endemic to a relatively small area with an area of occupancy smaller than 2,000 km² and the populations are severely fragmented. It has quite a narrow ecological tolerance and has clearly declined throughout much of its range due to threats such as pollution, changes of the hydrological regime of water bodies, and infrastructure development. It is therefore classed as Vulnerable.

Lansdown, R.V. 2013. Thorella verticillato-inundata. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 15 April 2015.

In Portugal, its distribution is fragmented.

Caropsis verticillo-inundata, synonymy of Thorella verticillatinundata (considered a priority by the Habitats Directive) - It is a plant with its small, residual populations, reason why its state of conservation is classified as "threatened".

The global status is Vulnerable (Walter and Gillet, 1997) as well as in the IUCN Red List of the International Union for Conservation of Nature and Natural Resources.

At the national level, it also receives the status of Vulnerable (Ramos Lopes and Carvalho, 1990).

It is legally protected by Directive 92/43 / EEC (Annexes II and IV).

Lansdown, R.V. 2013. Thorella verticillato-inundata. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 15 April 2015.