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

Helosciadium nodiflorum (formerly Apium nodiflorum), commonly called fool's watercress,[1] is a flowering plant found in ditches or streams and native to western Europe. It is a low-growing or prostrate perennial with pinnate leaves which have a vague resemblance to those of watercress. Helosciadium nodiflorum has short-stalked umbels of very small white 5-petalled flowers which are opposite the leaves and grow from the side of the stem at the leaf axils. It blooms in July and August.[2][3]

It is not a poisonous plant, but it could be easily confused with the allegedly poisonous lesser water parsnipBerula erecta (Huds.) Coville. It is common throughout England, Wales and Ireland but is much less so in Scotland.[4]


There are a number of hybrids involving Helosciadium nodiflorum:

AHelosciadium nodiflorum, closeup of umbel flowers.


  1. ^ BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
  2. ^ Fool's-water-cress Wild flowers of Ireland. Accessed July 2011 Apium nodiflorum Fool's-water-cress]
  3. ^ Apium nodiflorum (Fool's-water-cress) Online Atlas of British and Irish Flora. Accessed July 2011
  4. ^ Apium nodiflorum Peter Llewellyn Wild Flowers of the British Isles, Accessed 2011
  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.

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