Information on Field Penny-cress

Common Name: Field Penny-cress
Scientific Name: Thlaspi arvense
Irish Name: Praiseach fhia
Family Group: Brassicaceae
Distribution: View Map (Courtesy of the BSBI)
Flowering Period


Click for list of all flowering by month
Field Penny-cress is not easily confused with other wild plants on this web site.


This is an annual weed of arable soil, fields and fertile ground which stands to abou 60 cm high. It does not have a basal rosette, but its erect stems have lower leaves which are oblong, stalked and toothed, with the upper leaves being sessile, clasping the main stem. From May to August, the little white four-petalled flowers (4–6 mm) are borne in racemes, each flower having yellow anthers. The seeds are in oval, flat pods, each having a distinct notch. This is a hairless plant and it seems a shame that its main identifying feature is its unpleasant smell, but it's true. When the plant is crushed, it releases quite a foul smell. This is an introduced plant and it belongs to the Brassicaceae family.

I first came across this little plant on the side of a newly built road near Athy, Co Kildare in May 2010, when I also took the photograph.  Dr Declan Doogue, BSBI Vice-county Recorder for County Kildare, kindly confirmed my identification.  

If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre

Penny-cress, Field
Penny-cress, Field

Research is currently being carried out on this plant in the U.S.A. with the prospect of raising it as a fuel crop. Due to its toxic nature, it would never be considered as a food crop and therefore would not be in competition with other potential fuel crops such as soya and rapeseed.