Reseda luteola L., Weld

Account Summary

Growth form, origin, preferred habitats and uses

This tall (50-150 cm), robust, hairless biennial possesses a strong tap-root plus many side-roots and, as usual in plants of this biotype, produces a leaf rosette in its first growth season and a stiffly erect, ribbed, hollow flowering stem in the second. The tiny (4-5 mm), 4-petalled, yellowish-green flowers are produced in long, slender racemes, and the basal rosette of linear leaves withers after the first season. R. luteola typically grows in lowland areas on disturbed, neutral or base-rich, often calcareous, stony or sandy, neglected waysides, waste ground and disused quarries.

A definite native of the Mediterranean region and W Asia, R. luteola, 'Weld', 'Yellow-weed' or 'Dyer's Rocket' as the latter names imply, provides a natural yellow dyestuff and from Neolithic times it has been introduced and cultivated for its yellow flavone in many parts of the world, including B & I. Every part of the plant except the roots can be used for dyeing.

British and Irish status

Webb (1985) included R. luteola in his list of 41 species previously considered native in B & I, which he believed were probably introduced by man. The plant is very robust and produces a large crop of seed which is extremely long-persistent in the soil seed bank. In 1931, an archaeological dig at a first century ditch at Cirencester resulted in a crop of Weld appearing on three occasions. The suggestion that the seed remained viable for 1,800 years was described at the time as being, "not incredible" (Rees 1931, quoted by Salisbury 1964, p. 323). However, until the editors of the New Atlas (2002) recognised the species as an archaeophyte, all B & I Floras and other botanical works regarded R. luteola as native to these islands (eg Cen Cat Fl Ir 2; Clement & Foster 1994; New Flora of the BI 1997; Cat Alien Pl Ir).

Irish occurrence

The New Atlas map clearly shows that R. luteola is relatively frequent, more widespread and established in S & E Ireland than is the case in Fermanagh and neighbouring VCs. The hectad map shows that the species distribution lies chiefly in the Midlands and the SE of the island and the plant becomes increasingly rare and more confined to the coast as one moves in a north-easterly direction, ie it is most frequent E of the River Shannon and NE of Lough Neagh (Preston et al. 2002).

Fermanagh occurrence

There are just four records of R. luteola in the Fermanagh Flora Database, from waste ground spread across separate lowland tetrads. They date from 1884 onwards and only one of them is post-1975, but the latter, too, is now 30 years old! Clearly this is a very rare, only casual species in Fermanagh.

The details of the other three Fermanagh records are: quarry near Donagh Crossroads, 1950, MCM & D; old Ulster Canal near Gortnacarrow Bridge, 1950, MCM & D; Muckross near Kesh, 1976, Miss N. Dawson.

British occurrence

R. luteola is widespread and common in lowland Britain as far N as the Scottish urban areas of Edinburgh and Glasgow. It also has outliers further N around the Inverness area (New Atlas). In the past, the principal growing areas for the Weld dye crop were in Yorkshire, Lincolnshire, Essex and Kent and relics of these plantings may still persist in these areas alongside 'wild' plants (Sell & Murrell 2014).

European and world occurrence

R. luteola is considered native to the Mediterranean region and W Asia and, after a long period of widespread introduction and cultivation, it is a widespread weed in most of Europe northwards to around 66°N in Sweden and Finland. It extends eastwards to W & C Asia, south to N Africa and SW to the Canary Islands. It is introduced in N & S America, Australia and New Zealand (Hultén & Fries 1986, Map 997).

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