''Quercus lusitanica'', commonly known as gall oak, Lusitanian oak, or dyer's oak, is a species of oak native to

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

( Galicia and western Andalucia) and

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

. ''Quercus lusitanica'' is the source of commercial nutgalls. These

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or war ...

s are produced by the infection from the insect '' Cynips gallae tinctoriae''. They are used for

dyeing Dyeing is the application of dyes or pigments on textile materials such as fibers, yarns, and fabrics with the goal of achieving color with desired color fastness. Dyeing is normally done in a special solution containing dyes and particular ...

. Several other species are known colloquially as "gall oaks;" indeed, galls can be found on a large percentage of oak species. The specific epithet "''lusitanica''" refers to the ancient Roman Province of

Lusitania Lusitania (; ) was an ancient Iberian Roman province encompassing most of modern-day Portugal (south of the Douro River) and a large portion of western Spain (the present Extremadura and Province of Salamanca). Romans named the region after th ...

, corresponding roughly to present-day Portugal and

Extremadura Extremadura ( ; ; ; ; Fala language, Fala: ''Extremaúra'') is a landlocked autonomous communities in Spain, autonomous community of Spain. Its capital city is Mérida, Spain, Mérida, and its largest city is Badajoz. Located in the central- ...

in Spain.

Description

''Quercus lusitanica'' is a stoloniferous shrub, usually prostrate, under 3 m in height.

Taxonomy

It was incorrectly named ''Q. humilis'', later ''Q. fruticosa'' and its current name was incorrectly used to identify other Gall oaks from the Iberian Peninsula and North Africa. This resulted in numerous taxonomy errors in the Gall oaks taxa from the occidental and oriental Mediterranean Basin.

Distribution and habitat

''Quercus lusitanica'' is native to the

Iberian Peninsula The Iberian Peninsula ( ), also known as Iberia, is a peninsula in south-western Europe. Mostly separated from the rest of the European landmass by the Pyrenees, it includes the territories of peninsular Spain and Continental Portugal, comprisin ...

(in Portugal and western

Andalusia Andalusia ( , ; , ) is the southernmost autonomous communities of Spain, autonomous community in Peninsular Spain, located in the south of the Iberian Peninsula, in southwestern Europe. It is the most populous and the second-largest autonomou ...

, Spain, also rare on Galicia) and Morocco It is commonly associated in oak and pine forests and does well in acidic soils. It favors mild coastal

Mediterranean climate A Mediterranean climate ( ), also called a dry summer climate, described by Köppen and Trewartha as ''Cs'', is a temperate climate type that occurs in the lower mid-latitudes (normally 30 to 44 north and south latitude). Such climates typic ...

s but it also succeeds in moist, mild, maritime climates. It is relatively sensitive to cold temperatures and is hardy down to . It inhabits sandy or gravelly soils up to in elevation.

Threats

No serious threats were found in Portugal, though in Andalusia this plant has been listed as

Near Threatened A near-threatened species is a species which has been Conservation status, categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature (IUCN) as that may be vulnerable to Endangered species, endangerment in the ne ...

due to fires, silviculture and grazing

ungulate Ungulates ( ) are members of the diverse clade Euungulata ("true ungulates"), which primarily consists of large mammals with Hoof, hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined ...

s. The main threat to the conservation of genetic diversity of this species is the hybridization with the oak neighbors ( Holm Oak,

Cork Oak ''Quercus suber'', commonly called the cork oak, is a medium-sized, evergreen oak tree in the section Quercus sect. Cerris, ''Quercus'' sect. ''Cerris''. It is the primary source of cork (material), cork for wine bottle stoppers and other uses, ...

, Kermes Oak, Pyrenean Oak).

References

lusitanica Flora of Spain Flora of Portugal Trees of Morocco Trees of Mediterranean climate Oak galls Plants described in 1785 Plant dyes {{Quercus-stub