Barbarea intermedia Boreau, Medium-flowered Winter-cress
Account Summary
Introduction, neophyte, a widely naturalised weed, but rare and only casual here.
1939; Praeger, R.Ll.; around Enniskillen.
April to November.
Growth form and preferred habitats
Although this mainly but not exclusively biennial, naturalised alien species can generally be distinguished from B. vulgaris (Winter-cress) by its more dissected upper stem leaves (examine the top ten stem leaves and bracts) and, when in fruit, the shorter, stouter floral style (ie 0.6-1.7 mm long (average around 1 mm) in B. intermedia, rather than 1.7-4.0 mm long (average around 2.5 mm) in B. vulgaris). Also, B. intermedia starts flowering earlier (in March), than B. vulgaris (April onwards) (Rich 1991). These two weed species occupy the same sorts of disturbed habitats and they are sometimes rather difficult to separate in reality. For this reason, Robert Northridge and the current author both feel we cannot rule out the possibility of confusion in some of our own records of these two species, and that we need to bear this in mind when commenting on its local occurrence.
Fermanagh occurrence

The Fermanagh Flora Database contains B. intermedia records from twelve tetrads (2.3%), ten of which have post-1975 dates. This represents one-tenth the recorded presence of B. vulgaris. The main habitats of this winter-cress are disturbed ground on roadsides and waste ground, but they include a garden and a lakeshore too. As the tetrad distribution map indicates, this species is rare and casual in Fermanagh and appears very thinly scattered around the lowlands, with no obvious factor determining its distribution.
Rich (1987a) pointed out that nowadays in B & I, B. intermedia tends to colonise open habitats in disturbed ground on roadsides and building sites, whereas previously it was most frequently encountered as an arable weed. It is rarely if ever abundant, tending to occur as isolated individuals. Being both uncompetitive and ruderal, in Fermanagh at least, B. intermedia appears almost always as a casual species, cropping up in small numbers and soon disappearing.
Irish occurrence
B. intermedia is frequent to very frequent and widespread in N Ireland, especially in vice-counties Tyrone (H36), Armagh (H37), Down (H38) and Antrim (H39). It is particularly frequent around Belfast. The species is recorded to a much lesser extent in Fermanagh (H33) and Londonderry (H40) (Flora of Lough Neagh; FNEI 3; Urban Flora of Belfast). Around Lough Neagh, John Harron occasionally found it colonising lakeshore gravel and riverbanks, mostly in well-drained conditions. Apart from one 1957 record at or near Lough Melvin, none of the Fermanagh Database records match this type of habitat, where instead one might well expect to encounter B. vulgaris (Winter-cress).
B. intermedia was first found in the wild in the British Isles near Ballymena, Co Antrim (H39) around 1836. It might be more accurate to say it was first distinguished from B. vulgaris there at that time. It most likely arrived as a crop seed contaminant and became established in NE Ireland around the end of the 19th century (Cat Alien Pl Ir).
In the second edition of the Flora of NE Ireland, Praeger described B. intermedia occurring on waste ground and the margins of fields as, "a very local plant in Ireland, occupying a wedge of country extending from Galway to Tyrone and Down, and frequent only in the NE, where it is widespread but never abundant." (Praeger & Megaw 1938).
Perusal of the New Atlas map suggests that B. intermedia is particularly sparse throughout the RoI when compared to N Ireland to such an extent that David Pearman suggests it may be seriously under-recorded there (D.A. Pearman, in: Preston et al. 2002). The species has been recorded at least once from 28 of the 40 Irish VCs, and a hectad map of the BSBI database (accessed 1 April 2020) now shows it better represented in the RoI than in the New Atlas, especially in the SE counties of Waterford (H6) and Wexford (H12) which are expertly surveyed by Paul Green (Green 2008).
British occurrence
In Britain, B. intermedia is a frequent and widespread casual throughout the whole range of latitude, although it remains somewhat patchy in its distribution and becomes decidedly coastal in the N & W of Scotland (New Atlas; BSBI database accessed 1 April 2020). There has been an impressive increase in our knowledge of this weedy crucifer in recent decades. The index of change between the 1962 and 2002 Flora atlases (Perring & Walters 1962; New Atlas) has been calculated as + 1.92, indicating a very nearly doubling in records over that 40 year period. In their account of alien plants in B & I, Clement & Foster (1994) wrote of it being, "Locally established and persistent on arable and waste land in widely scattered localities throughout the British Isles; increasing."
Comparison of the hectad maps of the New Atlas survey (2002) and the current BSBI database 2020 survey shows there has been an increase in the cover of B. intermedia in both B & I, but especially so in S & W England. This suggests that this species is increasingly frequent and more widespread yet, as indicated above with respect to the Fermanagh experience, it is possible that it may sometimes still be overlooked or confused with the generally much more common and widespread B. vulgaris. Thus, perhaps what the hectad maps are really displaying is better field identification than was the case in previous surveys. Probably both these suggestions are true.
European and world occurrence
As with other species that have a history as arable weeds, it is impossible to be certain of the native range of B. intermedia. The species is considered 'probably native' in S & C Europe from N Portugal to S Denmark and S Germany and also in N and E Africa (Rich 1991). It is introduced in N Denmark, S Sweden and Switzerland and has a few additional outliers in C Europe (Jalas & Suominen 1994, Map 2307). It is also said to be introduced in Australasia (Rich 1991).
Threats
None.