Erysimum cheiranthoides L., Treacle-mustard

Account Summary

Growth form and preferred habitats

Treacle-mustard is a spring or autumn annual of open, well-illuminated conditions. It prefers light or sandy, medium dry to moist soils, but avoids more acidic ground (Fitter 1987). It can be frequent in arable fields, but is commonly found on lowland waste ground, including on walls, docks, roadsides, along railways and in gardens, often present in only small numbers (Rich 1991).

Flowering reproduction

Flowering occurs from June to September, or even for longer in milder areas. While the yellow flowers do produce nectar and insects visit them, essentially the species is automatically self-pollinated (Clapham et al. 1962; Garrard & Streeter 1983; Webb et al. 1996). Well-grown plants can each produce around 15,000 seeds, but in N America where this weed is common, the average productivity is greater at around 25,000 seeds per plant. The seeds are very bitter tasting, yet horses and cattle eat the plant and its fruit, since seed has been recovered from their droppings, indicating some degree of secondary dispersal takes place (Salisbury 1964, pp. 66 & 102).

Seed survival and germination

Buried seed of Treacle-mustard can survive for up to six years in soil (Salisbury 1964, p. 328). Roberts & Boddrell (1983) found that about 3% of seed were dormant and viable after five years burial. Almost all seedlings emerge during spring and summer with a peak usually occurring in March or April. Lauer (1953) recorded spring and summer emergence in Germany, and included E. cherianthoides in the group of species requiring relatively high temperatures for germination. Treacle-mustard is susceptible to modern herbicides and consequently it probably has declined in B & I during the past 50 years as agriculture has intensified (Rich 1991).

Fermanagh occurrence

There are only three records of this weed in the Fermanagh Flora Database, all from the mid-south of the VC. In addition to the first record listed above the details are: Gortaree gravel pits, Slieve Rushen, 1948, MCM & D; disturbed ground at Farnaght, SE of Tamlaght, 21 August 1989, RHN.

Irish occurrence

In N Ireland, Treacle-mustard is an exceedingly rare casual weed of disturbed lowland arable or waste ground. The New Atlas hectad map for Ireland shows it much more frequently represented S of a line between Dundalk and Galway and, especially so, in more inland Midland counties and around port docklands. Nevertheless, Reynolds in Cat Alien Pl Ir describes its Irish occurrence as being, "a fairly widespread but uncommon casual or arable weed ... nowhere thoroughly established".

British occurrence and status

E. cheiranthoides is frequent in SE England, occasional in the Midlands, SW England and in coastal parts of Wales. Elsewhere in Britain it is rare and casual − although it has been recorded in a scattered manner from the whole range of latitude (Preston et al. 2002).

The native range of E. cheiranthoides worldwide has been a matter of speculation and doubt for some time. It had long been given 'native' or 'doubtfully native' status in B & I, this at least applying to its stronghold in SE England (Jalas & Suominen 1994, Map 2244). With reservations, it was still accepted as native by Clement & Foster (1994) in their book Alien Plants of the British Isles. After recent reassessment it is now considered an ancient introduction (ie an archaeophyte), fossil evidence proving its presence in both Bronze Age and Roman settlements (D.A. Pearman, in: Preston et al. 2002).

In common with Sisymbrium orientale (Eastern Rocket) it is regularly (but probably as seed technology improves) increasingly rarely reintroduced as a contaminant of grain, animal feed and pasture seed mixtures, particularly those involving Clover from N America (Rich 1991; D.A. Pearman, in: Preston et al. 2002; Cat Alien Pl Ir).

European and world occurrence

Beyond our shores, E. cheiranthoides is regarded as 'probably native' in E Europe, Siberia and western N America, but it has become so widely naturalised that it has colonised W Europe from 68N southwards to N Africa and has developed a circumpolar boreo-temperate distribution (D.A. Pearman, in: Preston et al. 2002).

Names

The genus name 'Erysimum' is a classical one, given to some plant, possibly of the same family, by Theophrastus, the so-called 'Father of Botany'. It is also possible to derive the name from the Greek 'eryo' or 'eruo', meaning 'to draw up' or 'to draw out', the name then supposedly alluding to the blister raising properties of some members of the genus (Johnson & Smith 1946; Gilbert-Carter 1964; Hyam & Pankhurst 1995). The specific epithet 'cheiranthoides', means 'like or resembling Cheiranthus', that is, 'Wallflower-like' (Hyam & Pankhurst 1995).

The English common name 'Treacle-mustard' from the 19th century onwards has been applied to this species but formerly it was a name given by Turner (as 'triacle mustard'), to either Lepidium campestre (Field Pepper-wort) (Britten & Holland 1886), or more likely, Thlaspi arvense (Field Penny-cress) (Stearn 1965; Grigson 1974). 'Thiacle' came from the Greek 'theriake', meaning 'antidote against a poisonous bite', so that the name 'Treacle-mustard' meant, 'mustard for a treacle or remedy' (Grigson 1974). According to Prior (1879), 'Treacle-mustard' or 'Treacle wormseed' was one of 73 ingredients used in making 'Venice treacle', a famous vermifuge and antidote to all animal poisons, which was in great vogue during the Middle Ages. Britten & Holland (1886) list another name, 'Tarrify' from the Cambridgeshire Fens, given, they supposed (on unfathomable grounds), "because it terrifies the farmer or the weeder".

Uses

In a recent dictionary of plant names, Watts (2000) comments that E. cheiranthoides is certainly a vermifuge (ie a wormer), "though it can be quite a dangerous one". AS WITH ALL SUCH HERBAL MEDICINES, EXTREME CAUTION AND USE ONLY UNDER PROPERLY QUALIFIED SUPERVISION IS ESSENTIAL.

Threats

None.

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