Daucus halophilus Brot. is considered in some taxonomic treatments as a subspecies of D. carota (D. carota ssp. halophilus (Brot) A. Pujadas). The taxon is closely related to carrot, D. carota L.

Daucus halophilus is assessed as Data Deficient. It is suspected that the population has decreased due to a decline in the quality and extent of habitat during the past 30 years, and that it may be continuing to decrease due to continued coastal development; mainly for tourism. However, analysis of the currently available data does not indicate that the population may have declined by as much as 30% (i.e. the minimum threshold to assess the species as Vulnerable). Further, despite the extent of occurrence (EOO) estimated to be 9,156 km² (i.e., below the minimum threshold of 20,000 km² to assess the species as Vulnerable), there are insufficient data available to conclude that the population is severely fragmented, or that the number of locations ≤10, and it is not known whether there are extreme fluctuations in the population. The available data are also insufficient to justify assessing the species as Near Threatened. A survey is therefore needed to collect the necessary data to reassess this species.

D. halophilus is endemic to Portugal where it occurs along the west coast, extending from the north to the south, as well as in the western part of the southern coast (Magos Brehm 2009). The extent of occurrence (EOO) is 9,156 km²—this was estimated from herbarium specimens collected between 1956 and 2005; specimens collected before 1956 were not included in the calculation. Note that this species occurs exclusively along the coast and as the EOO was estimated from the area of the convex polygon that encompasses the locations of occurrence, it also includes areas inland that are probably unsuitable for the species; therefore, the EOO value is likely to be over-estimated.

There is no detailed information about the population of this species. However, given that it occurs along the coast where tourism has been increasing (and hence the quality and extent of habitat has been decreasing) during the past 30 years (and continuing), it is suspected that the population is decreasing.

It is found in steep coastal areas, fossile dunes (Pujadas Salvà 2003), grassy areas near coastal cliffs, limestone, together with Crucianella spp., Helichrysum spp., Iberis spp. and Beta vulgaris ssp. maritima (Magos Brehm 2009). It grows in luvisol, cambisol and podzol and tolerates both acid, neutral and alkaline soils; however, a higher number of populations are associated with luvisol, and with acid soils. The taxon grows in temperatures ranging from 12.5–17.5ºC, with a higher number of records in the range of 16–17.5ºC. Radiation has been recorded in the range of 140–165 Kcal/cm² with incidence in 155–160 Kcal/cm² and sunlight of 2,400 to >3,000 hrs, with a higher number of records at 2,800–2,900 hours. It is found at sites with <400–1,200 mm of rainfall (with a higher number of records at sites with 400–700 mm) and 50–75 rainy days. The sites have <1–10 days of frost, with higher number of localities with <1 day (Magos Brehm 2009).

Although specific threats have not been recorded, some of the populations occur in areas where tourism and urban expansion have been intensive—at least in the last 30 years. Further, since the species occurs in areas where invasive species are a problem, it is suspected that invasive species are an additional threat.

A close wild relative of and potential gene donor to carrot, D. carota. It is a salt tolerant species and therefore is a potential donor for salt tolerance genes (Tavares et al. 2008). The same authors also showed that the oils of D. halophilus have a strong anti-fungal activity against dermatophyte strains. Further, the species can be used in restoring impoverished saline soils and to sustain sand dunes near the coast (Tavares et al. 2010).

The genus Daucus is listed in Annex I of the International Treaty on Plant Genetic Resources for Food and Agriculture.

EURISCO reports only one germplasm accession of D. halophilus stored in the Genebank of the Leibniz Institute of Plant Genetics and Crop Plant Research (EURISCO Catalogue 2010). Germplasm collection and duplicated ex situ storage is a priority for this species.

The species has been successfully propagated in vitro and plants regenerated both by shoot proliferation and somatic embryogenesis (induced in cotyledons and root segments) (Tavares et al. 2010). Plants obtained by these two methods have been successfully acclimatized and reintroduced in their natural habitats, showing that in vitro propagation is a useful tool to be used in the in situ management of the populations of this species (Tavares et al. 2010). Apart from this reintroduction project, populations are not actively conserved in situ, although it has historically been recorded in at least five conservation areas across its range.

Given the lack of detailed information on both the presence and health of the extant populations of the taxon, surveying and monitoring is needed. Since some of the populations occur within conservation areas, active in situ conservation (with a management plan) should be undertaken in these areas.