Species of the Month - March 2014

Hairy Bittercress, Popping Cress

Cardamine hirsuta

A common annual weed of the cabbage family.  It's very under-recorded in Argyll, due to its early appearance and disappearance, and due to its being most frequent in gardens, which are not on most botanists' itineraries.

Although the books say that it flowers all summer or even all year, in the west of Scotland it is very much a spring flower.  It starts in January, peaks in April and is rarely recorded after the end of May.  Possibly it goes on longer in gardens, where the soil is frequently disturbed bringing more of its seeds to the surface each time.

It is also found on waste ground and likes any dry, bare, sunny place whether natural or artificial.  In this it differs from Wavy Bittercress, the only possible confusion species, which prefers damp shady spots.  This difference is not foolproof however as Hairy B can occasionally be found in Wavy B's habitat.

The main points of difference between Hairy and Wavy Bittercress are as follows:

Hairy Bittercress


Wavy Bittercress

Pods overtop flowers


Pods not or hardly overtopping flowers

Stems not hairy above


Stems hairy above

4 stamens per flower


6 stamens per flower (2 may be smaller than the other 4)

Usually 1-4 stem leaves   Usually 4-10 stem leaves
Stems only slightly wavy   Stems notably zigzag

Cardamine hirsuta

Hairy Bittercress flower, showing the 4 stamens

Cardamine hirsuta

Hairy Bittercress growing in a shady mossy habitat that is more typical of Wavy Bittercress
  Cardamine hirsuta

An unusual very short-stemmed reddish form growing in well-drained sun-baked river shingle that is occasionally flooded

Cardamine hirsuta

Most of the leaves are in a basal rosettte but there are normally a few leaves on the stems too.  All the leaves are made up of several pairs of leaflets with a larger terminal leaflet at the end.  The flowers are about 2.5-5 mm in diameter.  The pods are about 10-22 mm long and 0.8-1.5 mm wide.

Cardamine hirsuta

It can be an annoying weed of cultivated ground although being an annual it does not have a deep root system and is easy to pull out.  It makes a tasty addition to salads.  It is often called Popping Cress due to the explosive way the pods open when ripe, scattering the seeds up to a metre away.

Please send in yo
ur Hairy Bittercress sightings using the form below, or email sightings@lnhg.org.uk with the details if you prefer.  If you are not sure of the identity of your plant, please send a photo to sightings@lnhg.org.uk, or put one on the LORN forum and let me know it is there.

Date of sighting 
Grid reference 
Name of finder 
Your name (if different) 
Email (not needed if I already know it!) 
Any other details   


By filling in this form you agree that the information contained in this form may be collated and disseminated manually or electronically for environmental decision-making, education, research and other public benefit uses in accordance with the LNHG data access policy.  Your email address will not form part of the record and will not be passed on to anyone.

Carl Farmer
G Biological Records Manager

Sightings so far

23 Mar: Seen in Oban bus station area with flowers and pods, Carl.

29 Mar: At Barguillean

1 Apr: Seen on Eriska

12 Apr: Seen by Judith in Glen Aray

14 Apr: Seen at Craobh Haven

Note you can still send in records for past species of the month.  Here is the list of species we've had so far:

Feb 2014 - Pale Brindled Beauty
Jan 2014 - Velvet Shank
Dec 2013 - Frilly-fruited Jelly Lichen
Nov 2013 - Whooper Swan
Oct 2013 - Ballerina Waxcap
Sep 2013 - Parrot Waxcap
Aug 2013 - Vapourer Moth

Jul 2013 - Emerald Damselfly
Jun 2013 - Globe Flower
May 2013 - Early Purple Orchid
Apr 2013 - Peacock Butterfly
Mar 2013 - Oak Beauty
Feb 2013 - Coral Lungwort

Jan 2013 - Willow Jelly Button & Birch Jelly Button
Dec 2012 - Dice Lichen
Nov 2012 - Feathered Thorn
Oct 2012 - Dryad's Saddle
Sep 2012 - Tawny Grisette
Aug 2012 - Forest Bug
Jul 2012 - Grayling
Jun 2012 - Greater and Lesser Butterfly Orchids
May 2012 - Small Copper
Apr 2012 - Green Tiger Beetle
Mar 2012 - March Moth
Feb 2012 - Barren Strawberry
Jan 2012 - Brambling
Dec 2011 - Red Squirrel
Nov 2011 - Hazel Gloves
Oct 2011 - Small Tortoiseshell
Sep 2011 - Fly Agaric
Aug 2011 - Grass of Parnassus
Jul 2011 - Golden-ringed Dragonfly
Jun 2011 - 7-spot Ladybird
May 2011 - Green Hairstreak
Apr 2011 - Townhall Clock

Mar 2011 - Frogspawn

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All photos and other content copyright Carl Farmer except where stated