Helosciadium nodiflorum

Helosciadium nodiflorum[2] (synonym: Apium nodiflorum), fool's watercress,[1] is a flowering plant found in ditches or streams, as well as fresh and brackish-water wetlands native to western Europe. It is not poisonous to humans but it could be easily confused with the allegedly poisonous lesser water parsnip.

Helosciadium nodiflorum kz17.jpg
Scientific classification edit
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Apiales
Family: Apiaceae
Genus: Helosciadium
H. nodiflorum
Binomial name
Helosciadium nodiflorum


Helosciadium nodiflorum is a low-growing or prostrate hairless perennial up to 1 m tall, with a thick, hollow, faintly ridged stem which, when lying down (procumbent) produces roots at the nodes. It has glossy pinnate leaves, each of which has 4-6 opposite pairs of toothed, oval to lanceolate leaflets that are slightly paler green on the undersides. There are ridges at the nodes of the leaflets which are often paler than the rhachis and look like rings. (Note, this is different from lesser water-parsnip, which has a ring on the petiole.) The petioles are hollow with a distinctive single groove on upper surface, and may be streaked with red/purple lines; they are laterally inflated towards the base and clasp the stem.[3] The crushed leaves smell of carrot.

Close up of umbel flowers.


In 2010 a taxonomic revision demonstrated that the genus Apium was polyphyletic and needed to be split into three genera. Five of the 7 European species of Apium were therefore moved to the genus Helosciadium, as had first been proposed by Wilhelm Koch in 1824. Apium nodiflorum was among them, and is therefore now correctly called Helosciadium nodiflorum W.D.J. Koch.[4]

The genus is noted for the high rate of hybridization between its species, and the following hybrids have been described:

Distribution and habitatEdit

Helosciadium nodiflorum is common throughout England, Wales and Ireland but much less so in Scotland.[9] It often grows with watercress in wet places. It blooms in July and August and is found in wet habitats including ditches, springs, fens and ponds.[10][11] The species is also widely documented from brackish estuarine/salt marsh habitats.[12]


Wild fool's watercress has been traditionally harvested and consumed in several Mediterranean countries, including Spain, Italy, Portugal and Morocco[13] The edible young leaves and tender shoots can be used raw in salads, boiled, or used as a condiment in soups and other dishes.[14][15]


  1. ^ a b Lansdown, R.V. (2013). "Helosciadium nodiflorum". IUCN Red List of Threatened Species. 2013: e.T164030A13575513. doi:10.2305/IUCN.UK.2013-1.RLTS.T164030A13575513.en. Retrieved 16 November 2022.
  2. ^ https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:842893-1
  3. ^ Rose, Francis (2006). The Wild Flower Key. London: Frederick Warne. ISBN 978-0-7232-5175-0.
  4. ^ Ronse, A.; Popper, Z.A.; Preston, J.C.; Watson, M.F. (2010). "Taxonomic revision of European Apium L. s.l.: Helosciadium W.D.J.Koch restored". Plant Systematics and Evolution. 287 (1–2): 1–17. doi:10.1007/s00606-010-0284-3. S2CID 21921727.
  5. ^ Desjardins, Stuart D.; Leslie, Alan C.; Stace, Clive A.; Schwarzacher, Trude; Bailey, John P. (2015). "Intergeneric hybridisation between Berula erecta and Helosciadium nodiflorum (Apiaceae)". Taxon. 64 (4): 784–794. doi:10.12705/644.9. ISSN 1996-8175.
  6. ^ Desjardins, Stuart D. (2016-09-01). "Molecular confirmation of Helosciadium × moorei ( H. inundatum × H. nodiflorum ; Apiaceae) from County Cork, Ireland". New Journal of Botany. 6 (2–3): 90–97. doi:10.1080/20423489.2016.1271294. ISSN 2042-3489. S2CID 90980061.
  7. ^ Desjardins, Stuart D.; Shaw, Andrew G.; Webb, Judith A. (2020-02-26). "Hybridisation and introgression in British Helosciadium (Apiaceae)". British & Irish Botany. 2 (1): 27–42. doi:10.33928/bib.2020.02.027. ISSN 2632-4970.
  8. ^ Rita, Juan; Capó, Miquel; Moragues, Eva; Bota, Josefina; Cursach, Joana (2018-02-01). "Hybridization processes in an introduced subpopulation of an endangered plant: Management strategies to guarantee the conservation of Helosciadium bermejoi (Apiaceae)". Journal for Nature Conservation. 41: 26–34. doi:10.1016/j.jnc.2017.10.006. ISSN 1617-1381.
  9. ^ Apium nodiflorum Peter Llewellyn Wild Flowers of the British Isles, Accessed 2011
  10. ^ Fool's-water-cress Wild flowers of Ireland. Accessed July 2011 Apium nodiflorum Fool's-water-cress]
  11. ^ Apium nodiflorum (Fool's-water-cress)
  12. ^ envirolink.govt.nz (PDF) https://envirolink.govt.nz/assets/Envirolink/1624-HZLC127-Manawatu-Wanganui-Estuaries-Habitat-Mapping-Vulnerability-Assessment-and-Monitoring-Recommendations-Related-to-Issues-of-Eutrophication-and-Sedimentation.pdf. Retrieved 7 September 2021. {{cite web}}: Missing or empty |title= (help)
  13. ^ de Cortes Sanchez-Mata, Maria; Tardio, Javier (13 April 2016). Mediterranean Wild Edible Plants: Ethnobotany and Food Composition Tables. Springer. ISBN 978-1-4939-3327-3.
  14. ^ Parada, M; Carrió, E; Vallès, J (2011). "Ethnobotany of food plants in the Alt Empordà region (Catalonia, Iberian Peninsula)". Journal of Applied Botany and Food Quality (84): 11–25.
  15. ^ Guarrera, P.M.; Savo, V (2016). "Wild food plants used in traditional vegetable mixtures in Italy". Journal of Ethnopharmacology. 185: 202–234. doi:10.1016/j.jep.2016.02.050. PMID 26944238.

External linksEdit