Lactuca muralis (L.) Gaertn. is a wild relative of lettuce, Lactuca sativa L.

European regional assessment: Least Concern (LC)
EU 27 regional assessment: Least Concern (LC)

Lactuca muralis is regionally assessed as Least Concern. It is widely distributed throughout Europe and is common and widespread in many countries. It grows in a range of habitat types from lowlands to high altitudes and does not currently face any significant threats that would affect the European subpopulation as a whole.

L. muralis is native to and distributed widely throughout Europe, west to Turkey and the Caucasus, and is also native to north Africa (Morocco, Algeria and Tunisia) (Greuter 2006–2009).

Knowledge of its national distribution in Europe is as follows:

• Finland: occurs in the southern and south-central part of the country. 
• Germany: widespread across the whole country (Bundesamt für Naturschutz 2010).
• Hungary: frequent in the North Hungarian Mountains and Transdanubia, and sporadic in the Great Hungarian Plain (Little Alföld, Danube region, Danube-Tisza region:Monor, Pilis, Tiszántúl region: along the Tisza River, Szarvas, Nyírség, Dráva-sík) (Soó 1966, Simon 1992).
• Norway: present in the south, up to Nordland county.
• France: widespread; known to occur in all departments with the exception of Gers (Association Tela Botanica 2000–2010).
• United Kingdom: widespread throughout the majority of England and Wales; however, its distribution is patchy across Scotland (Preston et al. 2002). There are 19 localities in which this species occurs in Northern Ireland; however, they are all recorded as alien (Preston et al. 2002).
• Netherlands: infrequent in central and southern parts of the country (Mennema et al. 1985).
  

Knowledge of the European subpopulations of this species is as follows:

• Great Britain: according to Preston et al. (2002), the distribution of this taxon has remained largely unchanged since the 1962 Atlas was published.
• Netherlands: before and after 1950 the species occurred in 176 hour-squares (Mennema et al. 1985). Tamis et al. (2003) reported that the species is present in 301–1,000 km². The species does not show any decline in the Netherlands. 
• Slovakia: a common species (Dostál and Červenka1992).
• Germany: common and widespread (Bundesamt für Naturschutz 2010).
• Norway: quite common (Å. Asdal pers. comm. 2010).
  

This species grows in forests, along water courses and in secondary habitats, from lowland to high altitude.

It has been reported nationally to grow in the following specific habitats:

• Finland: shady herb-rich forests and rocky sites as well as springs.
• Germany: eutrophic sites, acidic forests, open woodland.
• Hungary: beech and hornbeam woodlands and dry oak forests (Quercetum petraeae-cerris), Querco-Fagetea species (Soó 1966, Simon 1992). It grows in a range of soil types but favours nitrogen enriched, fresh, loose loam and sandy soils.
• Great Britain: shaded walls, rocky outcrops, hedge banks, in woodland, wood margins and scrub (Preston et al. 2002). It prefers chalk and limestone but has also been found to grow on acidic rocks (Preston et al. 2002).
• Netherlands: pioneer vegetation, humid walls, forests and shrubwoods with a moderately fertile soil, which can be weakly basic or acid (Tamis et al. 2003).

It is threatened in some localities by building work and reconstruction/restoration of historic sites.

L. muralis is a wild relative of and potential gene donor to lettuce.

Knowledge of the national threat/conservation status of L. muralis is as follows:

• Denmark: Least Concern (LC) (Den Danske Rødliste 2010).
• Hungary: not protected (Király 2007).
• Finland: nationally classified as Least Concern (LC), but considered as Regionally Threatened (RT) within its northernmost region of occurrence.
• Germany: it is not threatened and not protected (Bundesamt für Naturschutz 2010).
• Netherlands: Least Concern (LC) (Mennema et al. 1985).
  

No germplasm accessions of L. muralis are reported by EURISCO to be held in European genebanks (EURISCO Catalogue 2010). Germplasm collection and duplicated ex situ storage is a priority for this species.